I am in the same situation, however my son is soon 4 years old.
Do everything you can to keep contact and have a loving relationship with her. Love between father and daughter is the best way of breaking the indoctrination.
Send a message to "Driving Force". He has a teenage daughter too and wonderful advice how to go about it.
I copy paste a thread of him:
Driving Force
I have raised two kids, both girls. The oldest who is now 29 decided when she was 14 that she did not want to go to meetings etc. That was her choice and my wife tried everything to get her to do all the JW stuff etc., I personally never pressured her, after all she was my step daughter and I followed the WT advice and leave discipline to the natural parent. I can tell you, this advice does not work. The step parent should get involved. Anyway that is not the issue here, that was just to give you a little background information.
When I learned TTATT and started my fade I needed some support and went and got professional help, much of our discussions were on how to keep my daughter, who is now 15, from becoming a JW.
Things not to do:
1. Never demand loyalty from your child. A child naturally loves both parents, even an abusive parent, because the child has no way to make comparisons, life's experience is very limited.
2. Never talk TTATT to the child, he will not understand and if he goes to meetings with his mother then there is the indoctrination to deal with and will only lead to alienation, and quickly bring up the subject (in the child's mind) about loyalty. "If I stop going to meetings I will upset mom, if I keep going I will upset dad." No child, and a 14 year is still a child, can mentally solve this dilemma, and this will lead to physical symptoms like stomach ache and headache, and even worse. I experienced this with my child, she frequently had headaches and my wife took her to many doctors, and many tests were done. Now that it is clearly defined no more JW stuff for my daughter the headaches have stopped. But reaching that stage was a difficult process for me.
3. Never stop the child from doing JW stuff with the other parent. This may sound odd, but it is the right thing to do. The child is probably coerced into doing all the JW stuff and will develop an aversion, this happens to us all and makes us feel trapped, and at some point we look for a way out. Your child will look for a way out and he must see you as a way out.
Things to do:
4. Offer your child an alternative. This is something that is not so easy to do. I do not mean an alternative religion, but an alternative life-style. Hobbies are a good thing, do it for you-self, and make sure you really enjoy it and let the whole family know, you are enjoying life. Of course you make the offer to your son that he can join you any time he likes, but again make sure you do not bring him into this loyalty question. If he wants to go along with you make sure this what he wants to do and he is not doing it to please you. Offering your child an alternative may even mean moving out and living alone, but enjoying life afterwards and having regular contact with your son so that he can see there is an alternative to JW life.
5. Offer yourself as an expert on what is correct and not correct regarding JWism.This means that you know TTATT and just letting your child know that if he wants to know why you think the way you do, he just needs to ask. Never volunteer information without it being asked for.
Those are some rules that I worked out with my psychiatrist and applied with my daughter and what are the results?
1. By going to the meetings my child saw/heard how I was referred to in the congregation, as an apostate deserving of death, someone even told her I was mentally diseased, but she saw me everyday. I bought a motorcycle and go out regularly. Took up beer-brewing and enjoy the beer every evening. Beekeeping was a hobby I had anyway, but my daughter clearly saw this brought me pleasure. Admittedly none of these things are typically female hobbies, but they showed my daughter that there is a life after the JWs.
2. A couple of months ago my wife went on holidays with some JW friends for two weeks, I stayed home and my daughter stayed with me. I allowed my daughter to do all the things that a normal 15 year old would do, there were strict rules that she had to follow for her own safety and I explained clearly why these rules were set, that they were not arbitrary. After the two weeks, she now has a boyfriend, a normal thing for a 15 year old. One of the most profound things she said to me later was, that after spending much time with her boyfriends' family is that "Worldly People" are not bad at all, and she realized that what the WT says about "Worldly People" is really not true, they are very nice. The sincerity she showed when she told me that brought tears to my eyes.
3. I decided to move out, see my OP on this. When I told my wife this, she immediately challenged the loyalty of our daughter, "Who do you want to live with?" My daughter decided that she wanted to live with me. Why? Because she does not like the JW way of life.
4. My daughter asked about TTATT, so she is now informed, but that was on here terms, when she was ready she asked.
I am not happy that my marriage has broken because of religion, but I am very happy that my daughter has made an informed decision against the JWs. Maybe what I have written can help you with your son, I hope it can.