How to help your child to stop wetting the bed at night?

My boyfriend has a 5 year old daughter and she still wets the bed at night. We're trying to help her stop that. We try waking her up at night to go the the restroom but she fights us cuz she doesnt want to get up and go. Or she'll get up but just sit on the toilet for a sec and say shes done but she didnt go at all. When she wakes up in the morning shes completely soaked in pee. We ask her why she wont get up and all she says is because she doesnt want to wake up at night. We even tried not giving her anything to drink a couple hours before she goes to bed but she still ends up wetting the bed at night. When shes at her aunt and uncles though, she will get up and go so we dont know why she wont go for us. What should we do?