I don't disagree with spankings, but I think at the age she is at, and with her acting out, it would only exacerbate the situation and backfire possibly make more trouble for you.
What are the consequences when she waltzes in the door?
Let her think she has accomplished sneaking out, play bad cop... do a stake out. Follow her, embarrass the hell out of her when you drag her young, rebellious behind home. 15 is far to young and ignorant these days trying to pass as grown! Maybe 50 years ago...
Even go as far as to tell her you are driving her to the police station because you are not living like this.
Take everything from her room but the bare essentials. No tv, no music, no phone, no boy. Even go so far as to take away her favorite clothes or shoes if you have to. Make her get a job and increase responsibilities. Make your home a cozy little boot camp
I had a sister who acted out and ran away. I had to sit through family counseling a lot. Some of which she didn't even show up for! I know how frustrating it can be. Hang in there.