Oh the toddler battlefield! They try the tricks on us that work at home and it can be confusing for them when they realize they don't work at d/c. I would put her on the potty before rest time and the put her on the mat with some books and a quiet toy. When you check on her and she is still on the mat congratulate her and remind her of the rest time rules. If she comes off the mat tell her you are not pleased, remind her of the rest time rules and then give a stern look. I had the same experience with a dcg. It was a battle of wills for a week, but she learned in about a week that I wasn't budging on the rules.
I need a little vent. I just had a dad call 3x in 5 minutes during naptime as I had a messy potty butt to wipe. I answered the third time to "oh I quess it's naptime" to which I replied "not anymore, I'll have to give it another try to settle them" dad ignored this and said he thought his son didn't need a nap anymore as he is up late every evening. I reminded Dad that his seasonal schedule change has given his son more time to sleep(they come later) in so he may want to rise him at his regular time because here, he still needs to nap. He was a little flustered at more forth right approach but seriously, I will not sacrafice the quiet of nap/rest time so this Dad can sleep in.
O.K. I feel better now.