I don't know/can't remember what her punishment was/is from the first attempt but...
If you've grounded her from everything and taken away her learner's permit/license (or the chance of getting that), what does she have to lose by sneaking out again?

I'm not saying grounding her was wrong (far from it!) but she may think that she's so far in the hole, another slip up isn't going to hurt anything. Skewed thinking? You bet!! (but she's a teenager lol)


My suggestion (keep in mind I don't have kids - so take it for what it's worth):
If "minor" punishment (aka mom and dad's punishment) isn't enough, wait till you know she's sneaking out, have the phone ready, and report her to the police as "out after curfew." Make her pay the fine (if there is one).

You might call an officer and ask about run-away criteria, too; here, they can't do much but pick them up and take them home, but the car-ride home might be enough to keep her from doing it again.