Has she got any friends, eg at nursery, who are out of nappies?
We found with DD that what pushed her to want to do it was knowing two of her little nursery friends were in pants and using the toilet, and us talking about it as part of them being 'big girls'.
I remember a conversation that went something like:
DD: Willa did a wee in her pants today
Me: Oh did she? Is Willa wearing big girl pants instead of nappies now?
DD: Yes. Sophia wears pants now as well.
Me: Do they try and do their wees on the toilet?
DD: Yes.
Me: Ooh, aren't they big girls now, wearing big girl pants and using the toilet!
A couple of days of her seeing and pondering this, and she was asking when she could wear pants instead of nappies, which meant she was very invested in cracking the potty. She literally learnt in a day, whereas when we tried 3 or 4 months earlier she didn't get it at all.