Bright sunlight at midday is what helps reset the body clock - according to someone who has suffered through this for years. I tried it for myself and am happy to say that it helps. Can your DD go outside to the playground or some such place during her lunch hour? There is no guarantee that it would work, but, no harm in trying. Also cut out the electronics at 6:30pm or before that if her sleep time is 8:00 pm. Good luck.
We are getting near the end of 8th grade so except a tea break, no going outside during the day. I might see if DD sleeps better in the summer when she is outside more of the time. We have always made sure she quits electronics 1 hour before bed. Perhaps it would help to close it down even earlier. It will be something else we can try once she is off melatonin..This week has been no nice as DD is going to sleep quickly due to the melatonin.