567—81.15 (455B) Upgrading of certificates. A person holding an unexpired certificate may upgrade the certificate by examination to a higher grade in the same classification in accordance with 81.7(455B), 81.9(455B) and 81.10(455B). The expiration date of the upgraded certificate shall be the same as the unexpired certificate. A person who upgrades a certificate during the biennium must also renew the upgraded certificate in accordance with 81.13(455B) and 81.14(455B, 272C) to maintain the person’s certification.