Why is she doing this and how can I get her to stop?

skroops

Zoey has been completely potty trained since like September, but she still wears a diaper at naptime and bedtime.  Recently she has started to strip down and take off all her clothes and diaper at basically every nap and bedtime.  At first I thought it was because she could feel that she was wet in the cloth diapers, so I switched to disposable pull ups thinking they would help her not feel the wetness.  It seemed to help a bit at first, but now she is taking the pull ups off too. 

And now these past few weeks, she will take the pull-up off and purposely pee on the floor of her room.  I will make sure that she goes potty right before we go upstairs for naptime/bedtime, but it doesn't matter.  It's like she doesn't completely empty her bladder just so that she can pee on the floor. Ugh!  What the heck?  I am so frustrated and sick of cleaning up pee all the time, but I have no idea how to get her to stop. 

Any thoughts?