My potty trained daughter has started having accdents: Thoughts?

Hey mamas. I need much-needed advice. My two-and-a-half-year-old daughter has been potty trained since she turned 2. About two months ago, she had been peeing in her underwear a little and then saying she has to go potty. Well, the past two weeks, she started FULLY peeing in her underwear. I have tried asking her every 30min. She always says no and pees 5min later in her underwear!