Each certificate of registration shall terminate on December 31 of the calendar year for which it is issued. The Service shall send a letter to each registrant notifying the registrant of the impending termination of the registration and providing instructions for requesting renewal. The registration may be renewed in accordance with §§ 800.33 and 800.34. Failure to receive the letter shall not exempt registrants from the responsibility of renewing their registration if required by § 800.31.