14 CFR § 61.427
What must I do if my flight instructor certificate with a sport pilot rating expires?
July 13, 2020
You may exchange your expired flight instructor certificate with a sport pilot rating for a new certificate with a sport pilot rating and any other rating on that certificate by passing a practical test as prescribed in §61.405(b) or §61.183(h) for one of the ratings listed on the expired flight instructor certificate. The FAA will reinstate any privilege authorized by the expired certificate.