So, we decided to try our own, go at her own pace method. I broke down and bought some disposable training pants (I thought about using cloth but I didn't want to make the investment). We put her in the training pants and ask every hour if she needs to go, when she says no we leave it at that and don't push.
After about 3 weeks we started to see her stay consistently dry so we tried underwear again with much better success. We are now working on her recognizing the need to go and telling us.
We are still using training pants during sleep but I'd guess that she'll be nap trained by the time she goes back to school in 6 weeks!
The most valuable lesson I learned from this experience is that each child is unique and you can't force a child to potty!