My grandson has Asperger's and his school is not making any changes. What I've read is that with the new change Aspergers just becomes a part of the continuum of autistic. The diagnosis gets a new name but it's still the same.
I suggest you ask the school this question. I suspect that you're misunderstanding of what the school is doing when they're calling for a meeting. I doubt very much that they are asking to start over. They may need to change the wording on the plan already set to go into place.
Later: I don't understand why your process is taking so long. Has your daughter been evaluated by the school office that handles such evaluations or are you trying to get them to accept a diagnosis made by an outside person? The office is called The Intermediate Education Service District in our school district. It's a county office that works with the school districts and runs the special education program.
My grandson has had private evaluations which are included in the Service District's plan. The Service District plan is administered by the school my son attends.
My granddaughter is ADHD and has a 504 plan. She received only a diagnosis by her pediatrician. Her school then convened a committee that included several different people to devise the plan. First the school/district people wrote up a suggested plan and then met with my daughter to discuss the plan. The whole process took less than a month once it was understood that ADHD was her difficulty. It did take time and trying out different ideas before a definitive diagnosis was made. The committee meets once a year to evaluate the plan and make changes if needed.
My grandson is in a special school that only teaches special ed students. His committee meets as needed.
Other posters have suggested that you need to fight for your daughter. Yes, but I suggest that the best way to do that is to show a co-operative and questioning attitude. The school people want to do what is best for your daughter within the limits of what the law and the district policies are. We really do catch more flies with honey than vinegar.