If this school district has a rule that a student needs to be on a 504 for a year before they will do a special ed eval:
1- Get this in writing.
2- File a complaint with the state using 1 as evidence.
3- Ask who the school's 504 coordinator is and request a 504 meeting so a 504 can be drafted and put in place.
4- Request that the prior school send a copy of the 504 the child had when the IEP went away. See if they can tell her the date it started. (It might exist - parents are not required members of the 504 team. And if it's been in place for a year it might be time for an IEP.)