Hmm... I think early bedtime will be the way to go. She's never in her life gone to bed before 9-9:30. That would rock her world. She never napped either, but that's for another post.
It would be hard to even take away reading for pleasure or really anything else- as an immediate punishment. The kid could entertain herself with dryer lint if need be.
I guess I should also say we have been trying to address this earnestly for several months. We had never really connsidered it a gifted issue. Since I posted here afew weeks ago, we have made progess. The feedback has been immensly valuable.