OP, you're in luck because I have been researching Chinese school options for my kids. I think your best bet if to find an adult class. Here is one based in Wootton HS:
https://www.wsclc.org/classes. Others offer bilingual classes but I think that will be tough for your child because most kids start at K/1st grade so by HS they are probably more advanced. The advantage of joining a Chinese school is that it opens up a lot of cultural activities your child could join because most of these classes have cultural classes and performances galore.
Another option, if your child is mostly interested in the language, is to do online classes from native Chinese speakers. I haven't researched this much but I know they are popular and know of many friends who do this for their kids. The sessions are super cheap (one friend pays $9 for half an hour!, another pays maybe $20/hour), so you could just use it to advance the language more.
Good luck and hope your daughter keeps on learning!