My daughter was doin really good potty training and then when we moved to a house where the bathroom is?

upstairs and now she just pees and poops in her underwear.i started puttin pullups on her again because i just am sick of cleaning pee and poop off her panties.she will be 4 on the 28th of this month.she should be potty trained by now.i have 2 other kids and never had this problem.i think she is just lazy and doesnt feel like walkin up the stairs to go.any ideas what to do?