You are right about Illinois, but here are a few things to consider. I'd guess it's much easier to deny a student entrance to gifted programming then to "kick" them out. Your daughter is and has been in the gifted program, so, that is in your favor.
Illinois does not require gifted programming, but your district currently provides it, that is in your favor.
There are many reasons to argue why a high IQ child would perform poorly on any test on any given day. Some argue that a child can score artificially high, which is why some districts like to do there own testing. I personally, don't think that argurment is very defensible.
Linda Silverman is an established professional in this specialty, also in your favor.
From what I've heard, you can sue successfully for accomodations in certain circumstances in Illinois. I'd guess it might cost upwards of $20,000, and I wouldn't hold out to get any of that back for damages.
I agree with Grinity, you should contact LS yourself and figure out what to do next.
These are merely my opinions, I'm not a lawyer, but I wish I was! I'd love to be able to help you!!
I wish you much success in helping your daughter.
