E.B.
Have had three girls...the tricks that we found work...
1. no liquid after 6pm
2. Wake her up before YOU go to bed and take her half asleep to the bathroom. THIS IS KEY! She may not be able to hold from 7pm-6am, but chances are much better she can hold from 7pm-10pm you take her... then she only holds from 10pm-6am. This also helps her to understand she will need to get up herself if she has to pee.
3. Read stories to her while she sits on the potty before nap. She will be relaxed and may get rid of that tiny bit of pee before nap. Let her pick 3-5 books, so she will be there a while.
4. Buy smaller wet pads to throw in the wash, rather than having to do sheets and the full rubber sheet. Then you won't be as bummed out about the accidents.
Hope it helps!
(#2 IS THE MOST IMPORTANT)