A man enlisted under this Part of this Act in the Territorial Army or in the Royal Auxiliary Air Force—
(a)may be re-engaged within the period of 12 months expiring with the end of his current term of service for such a period as may be prescribed, not exceeding 4 years from the end of that term, and
(b)on that re-engagement shall make the prescribed declaration before a justice of the peace or an officer,
and so from time to time.