Have you considered shortening her night?
For a while, we kept my DS napping by waking him in the morning after 10.5 hours of sleep (I've seen other mums have success waking after 11 hours of sleep). This creates enough sleep drive that LO is tired enough to nap. It may be a bit tricky to implement as it sounds like your DD is OT and not napping.
One option (this might sound crazy) would be to try some AP in order to get your LO caught up a bit and to get her body back into the swing of taking a nap. Will she fall asleep in the car? You might plan a car nap for a day or two, followed by intentionally short nights and see if that gets her back in synch with having a nap.
Another option, might be to try an earlier bed time.
I was just going to post a link to the support thread for dropping naps, but I see you've posted there already!
Hope you pick some helpful ideas!