Two part answer.
Part I. Review your validation procedure to see how often you need to revalidate. Usually once every 3 years, but you set the revalidation schedule. Unless a specification changed or a process change, usually the revalidation effort is minimal.
Part II. What is the basis for their requiring annual recertification? If it is a RoHS requirement (especially for the lead), they should have specified in the purchase order or contract. There is no requirement that this testing is done annually (well none I know of).