Have tried lots of things myself, not sure what will work. Some days I seem to making progress, then two steps back.....I think showing unconditional love is very important, but quite difficult when not shown in return, because the org comes first......
I try to ask questions, there are some good ones on this board. Make her aware of strange little nuances that she may not know about, for example I asked her how the bible supports the selection of the JWs as the true religion in 1919......she said she will need to talk to her study sister for that....
Tuesday has some really good 'tough questions for JWs', not all of them will apply in every situation, but they have helped me do a bit of thinking here and there and formalate some ideas.
One thing I found that does not work, and was warned against this and tried it anyway, is a full assault against the doctrines....bible ping pong does not work when one has had critical thinking skills diminished........
Best of luck, hope we get some more ideas here and develop this thread....