I would consult your states' law on special education.  Each state has different perimeters to follow.  Usually, it is determined at the ARD meeting for the child when the assessments will take place and how they will be measured.  (once every year, once every 2 years, etc) If it is determined the child no longer needs to have intervention, it must be agreed upon by all members of the ARD committee, that would include the parents.  If any member disagrees...lets say the parents disagree, the state must continue services at least 30 days.  The parent can request a parent advocate or mediation to reach an agreement, or can request additional outside testing to prove their point.  If the school still disagrees with the parent, there is an additional waiting period before the interventions can be pulled, and the parent has the option to appeal, bring in a lawyer or another specialist.  The interventions cannot be pulled arbitrarily, no matter which state you reside in.