I'm so sorry to hear this. I would make an appointment to speak to the principal tomorrow. Tell them that you will be coming, s/he will be there, and also in attendance will be a guidance counselor, the schol psycologist, the school police liason (if there is one), and a representative from the Superintendents office there. Do not give them a choice. Let them know that you would like to handle this nicely, but if they will not work with your daughters best interest, they will be speaking to your attorney instead. Do not let them blow you off, say people can't make it. They can rearrange their schedules to accomodate you. If you get there and some of those people aren't there, sit back in your chair and let them know you'll wait until they arrive. Then be quiet and make them squirm--which they will do. It's an old sales technique and it works every time, even in instances like this.
Put an action plan IN WRITING as to what the school will do to protect your daughter, and how they will manage this situation moving forward. Get a copy.
Follow up with the police department. Call your DA, and let them know that this was premeditated as part of an ongoing series of events. Ask them to consider filing charges against this girl as an adult.
The school has a DUTY to safeguard your daughter. They knew from previous events that there was an issue, and were negligent in their duty. In all honesty, I would strongly consider hiring an attorney.
You might also want to file a report with your state Child Protective Agency.
I would strongly consider getting an order of protection, even if it means the attacker has to change schools. Your daughter is the victim, do not let the district try to bully you inot making her change schools.
I would NOT accept a phone call of any type for any reason from the girls parents or insurance company. If they call, refer them to your lawyer.
The squeaky wheel gets the oil. Start squeaking and good luck!
Anne