Hi, and welcome
Have you wonder why the school is not working with this girl? From what I have observe and experience, is the girl has fallen in the range of high function autism. Like other categories such as LD, children who fall into the mild to moderate groupings, are seen differently by educators as opposed to the severe groupings. Schools actually feel that providing help in areas of their learning problems, will not be worth the effort in terms of increase grades, since many feel that they have reach their potential. I call this BS, but it is a way for schools to keep down the costs of special needs children who fall into the mild to moderate groupings.
I would suggest, from a parent perspective that to look at schools that provide for learning disabilities. The reason why, is that high functioning autism children, often have some of the same learning weaknesses as LD children. This girl would benefit from taking specific and targeted therapy, that addresses the learning weaknesses. LD schools are known to target the weaknesses, and not just re-mediate the weaknesses. Well, the good ones do; so watch for this when looking at these schools. Depending on the problems of the girl, LD schools usually take on the high-functioning autism children because they often have learning problems that are the same as children with a learning disability.
Also check as to how many students go on to higher learning in post-secondary sector. A lot of colleges have found these students better adept at navigating college, as opposed to students who are coming out of public education.
Good luck in your search.