The district, AND YOU, cannot file charges. They're not the District Attorney. They can file a complaint, then the POLICE DEPARTMENT refers the evidence to the DISTRICT ATTORNEY who files criminal charges.
All you can do is file a complaint with the PD, and THEY file charges. Not you, not your ISD.
At best, it's likely your PD will issue a citation for disorderly conduct. That's a minimal fine, doesn't require criminal charges, and often doesn't even result in a DAEP placement on its own. One hit to the face may not rise to the level of assault on a public servant - because that's literally a permanent life-changing set of criminal charges and JJAEP placement.
Her current behavior contract may be an escalation of her previous offenses, but I'm not privy to that information. If the child wasn't arrested at the scene (and booked, handcuffed, read her rights, etc), she's not likely to see lasting consequences. She'll likely get a slap on the wrist and be back at your campus next year, maybe at the start of the second six weeks if your district "holds her accountable" with a 45 day DAEP placement.
That's part of why you need a lawyer. You need someone to stand up for you.
Good luck. Get legal advice from a real lawyer ASAP. No one at your district has YOUR rights and best interest in mind - their folks are paid to protect THE DISTRICT.