If you aren't already, do your "wind down" routine away from her room with snuggling, singing, whatever works works for you. Make sure she is not hungry, wet, thirsty, and also not recently stuffed from a meal. Consider bumping the time you put her down to a little later so she is a bit more tired, but not miserable (that always makes things worse) and start by leaving her for at least 15 minutes at a time. We've had to change and adjust our nap routines so many times, and now my oldest doesn't nap and my younger one does, but he might go down anytime within a two hour range, depending on the day. If he really isn't sleeping, I bring him back downstairs and let him play then try again. It will definitely make things easier when she switches to a twin bed if she puts herself down well now. I would get her up, play quietly, read, and put her back in bed a little later, maybe closer to 3.