I remember seeing an ad for free online high school. It was specific to CA, but I googled and found this site where you can find ones that are credentialed for your state.
http://www.k12.com/schoolfinder.html
I don’t know much about this option but it may be worth looking into for you. I’m guessing it would be like her transferring to another HS and then transferring back to her local HS.