lkaufman, you can’t force her. She has to want it for herself. You have to accept that might not occur for a while. You can mention it to her, and see how she reacts to the idea. Explain that it’s a weekend in a hotel, no pressure at all, etc. You can even offer an incentive to her, as most hotels where they hold these events have a spa. Offer to pay for a spa treatment on motzei Shabbos if she attends lectures over Shabbos.
One other option you might want to consider is Neve in Israel. My wife went there, and it played a huge part in her becoming frum again. I know many friends of hers who also did very well there, including one girl who came in claiming she had no interest being frum, and was going to spend exactly one week there, no more. That girl ended up spending over a year there, and is now married to a guy who’s sitting in kollel. It might be worth looking into. They can probably also advise you on how to convince her to go there at all.