The board has power to grant leaves of absence and to grant extensions thereof to apprentices registered under the provisions of this chapter. However, no credit shall be given to an apprentice upon his or her apprenticeship for the period during which he or she is absent from duty on leave, and no more than an aggregate of 12 months’ leave of absence shall be granted to any apprentice during the term of his or her apprenticeship. Application for leave of absence and for extension thereof shall be made by the apprentice upon a form provided by and addressed to the board. Upon the termination of a leave of absence or any extension thereof, the apprentice shall report to the board the fact that he or she has resumed his or her duties as an apprentice and certified to by the funeral director under whom he or she has resumed his or her duties or by the embalmer under whom he or she is apprenticed, confirming this fact. Failure to so report within 30 days after the expiration date of any leave of absence or extension thereof shall automatically cancel the registration of the apprentice.