If it were me I would just buy a cheapie package of pull ups or diapers and put them on her at nap. Saves her the added pressure/stress of worrying about peeing the bed and getting trouble. I think there is more going on ... Maybe something at home.... But some kids use it as a power struggle and some just sleep too soundly to wake up to pee. My own son is 3.5 and still wears a diaper at night Cause he pees and I don't want to change the bed every time. Sober ones he goes a week or two with out wetting in the diaper and just when I think maybe its time to go without he pees in it.