Yizuman,
Generally, no, I did not, nor would I go back to any I participated in DFing. Why should I? I accepted the religion for what it was, acted in good faith in accordance with its rules, and when I was guilty of wrong, took it upon myself to tell the Elders and receive discipline just the same. The JWs are a religion ... and even though we do not believe it anymore, we should not have to go about apologizing for living by its precepts and rules ... unless we truly harmed someone in a serious way, on a deeper human level, that should not have happened in the first place. I know of no one whom I so harmed.
I did try to contact some of the individuals I helped to DF, not to apologize, but to see if I could help them not return to the organization. But they would not speak to me because some considered me apostate, or in some cases were themselves trying not to violate Watchtower rules, thinking they were protecting me from talking to a DF'd person. So, it was not a practical matter either.
If I ran into a DF'd person whom I sat on the JC that DF'd the person, I would share in restoring our relationship ... but I would not apologize unless the person expressed some concern that they felt they needed an apology, and could explain why they felt I owed them an apology.
One person I helped DF was a child molester ... the JC I served on DF'd him for smoking ... but later on he was nailed by another JC for child molesting. I would never consider contacting him. I did turn his name over to be sued along with the Society, and offered testimony against him.