While there are no specific time lines, some professionals recommend that students be re-evaluated at least every three years or whenever there is going to be a "significant change in placement." The campus 504 committee should reconsider the student's plan every year to make sure that his or her accommodation plan is appropriate, based on their current schedule and individual student needs. The accommodation plan may be revised during the school year if needed.
If a school district re-evaluates a student in accordance with the Section 504 regulation at 34 C.F.R. 104.35  and determines the student no longer meets the definition of a person with a disability , the student is no longer eligible for services under Section 504 of the Rehabilitation Act of 1973 .
For answers to basic questions pertaining to the implementation of Section 504 in public school systems read A Parent's Guide to Section 504 .
For a comparison of the three major laws that impact education rights for students with disabilities visit, an Overview of ADA, IDEA, and Section 504 .
For additional information on Section 504 and Section 504 education plans consult the DO-IT Knowledge Base articles, What is Section 504? , What is a 504 Plan? , and What is the difference between an IEP and a 504 Plan? 
-  Section 504 regulation at 34 C.F.R. 104.35
-  definition of a person with a disability
-  Section 504 of the Rehabilitation Act of 1973
-  A Parent's Guide to Section 504
-  Overview of ADA, IDEA, and Section 504
-  What is Section 504?
-  What is a 504 Plan?
-  What is the difference between an IEP and a 504 Plan?