It's not always easy to get cooperation from schools without a lot of negotiation; our most successful discussions have been directly with teachers, trying various solutions which may or may not be formalized into his 504 plan. Many educators have both experience with and sympathy for conditions like ADHD, and are happy to try accommodations that may help. We've been pretty lucky for the past few years.
It is unlikely that the school will be able to integrate a really extensive exercise schedule into her day. Once she is in middle and high school, she'll get to walk between classes, but I assume she's still in a single classroom for much of the day.
You will probably want to try a couple of approaches: increasing her physical activity in general at home, and seeing if her teacher would allow "micro sessions" when your daughter needs to move around a little to refocus. A handful of jumping jacks or squats, a brisk walk up and down the hallway -- just a minute or two of minor physical exertion to clear her head. In my ten-year-old son's case, his teacher gives him some leeway to stand up and stretch for a little bit (particularly if they're working on a standardized test), as long as he is not making noise, disrupting other students, peeking at other people's work... and while I wouldn't say it's revolutionized his behavior or school performance, both she and I think it's an allowance that helps him stay mellow and focused as best as he is able.
This works pretty well for me, as an adult with ADHD, at work: when I'm feeling distracted, I wander to the breakroom for water, or to the bathroom, or over to a colleague's cubicle to brainstorm. When possible, I go jogging on my lunch break. I have the luxury of scheduling my own time, though; while I am optimistic that physical activity could have some benefits for your daughter, the challenge is negotiating that in such a way that it works for everyone involved.
At home, commit to allowing some sort of physical activity as much as possible. My son hates pretty much every team sport he tried, and we're now trying running. (He likes that in part because I let him use an old GPS watch of mine when we jog together.) I take him on trails for a mile or so with me on the weekends, we go to the park, he and his little brother run "laps" up and down the hallway in bad weather or after sundown... and there's always weight lifting, jumping jacks, pushups, crunches, or other calisthenics.