Sort of.
Unfortunatly it's called the Ladies room for the females and the men's room for the males.
You might also try to make friends with people at the con who are staying there, they might help you out and let the change in their room.
(Real World Disclaimer...PLEASE! Use common sense when going back to a hotel room with someone you just met! The buddy system is good. Especially if you are a young female, please try to find a group of girls.
The above is not an official con policy and does not imply that Con Management told you to go ask a stranger to let you change your clothes in their hotel room.)