I would just make her curfew even earlier than it is now. Then tell her if she comes home at that time like she's suppose to for a while, then you'll extend it back to where it was. If she again disobeys then punish her. Let her know that she was given a chance and not this is a one time thing but I'm going to ground you anyways.
Make it clear to her why she has a curfew. Then, take away anything that connects her to the outside world so she understands what would happen if she is late again. I'm a teenager and taking away things like that makes me nuts.