T.D.
If she's anything at all like my daughter, she probably doesn't want to have to stop playing to go potty and hates being dirty/wet so she figures she could wear a diaper, not make a mess and not stop playing. What finally worked for my daughter was a. I stopped buying pull-ups and only put a diaper on her at night (she battled for the diaper too, but I told her that she didn't get one and let her walk around naked until she chose to put on the panties I laid out for her...and she couldn't do _________ until she was all dressed) and b. I bought a potty watch--it is a "watch" with a set timer (30, 60, or 90 min) that lights up and plays a potty song then automatically restarts the timer. It worked wonders since I had a battle making her go potty at regular intervals, the potty watch tells her to go instead of me and no fights! Plus I don't forget to remind her to try. I got mine from www.pottytimeinc.com...they are rather cheaply made, but they don't cost much and do the trick!