Is it possible that she's aging out of the current accommodations?
I might approach the meeting that way-- as in, you're "flexible" and "willing to consider updates" since the original was (I'm assuming) written some time ago, and refers to policies, practices, and procedures in a different district... naturally you'll want her 504 plan to reflect the new school setting.
In other words, treat the 504 eligibility as a foregone conclusion... and treat lightly on accommodations (for now) until you have that part locked up tight...
if they push back on accommodations that YOU feel are really not negotiable, then back up your opinion with whatever expert opinion you can muster-- OT/physician letters, whatever.
