What are her feelings about math? (Does she typically love it, or is she all-around smart?)
What does she say when you tell her this will affect future track and placement if she goes down a track?
What are her feelings about being a "smart girl"?
Concerns about being "nerdy"?
Is this class largely boys?
What are the consequences for a poor grade in 7th grade? Does it matter?
Would she be willing to commit to nightly homework/comprehension checks with you?
I feel for you as we have experienced some somewhat similar issues, and still are.