Existing permits, subject to provisions controlling nonconforming uses, provisions of the Town Law, site plan regulations, subdivision regulations, and §§ 290-31E and 290-32C(3). This chapter is not intended to abrogate or annul any building permits, certificates of occupancy, variances or special permits lawfully issued, or preliminary site plans and subdivision plats approved before the effective date of this chapter. Notwithstanding any provision of this chapter to the contrary, no special permit or variance hereafter issued shall have any force or effect for a period greater than 12 months after the date of its issuance by the Town Board or Zoning Board of Appeals, and any special permit or variance heretofore issued shall expire 12 months after the effective date hereof. Prior to such expiration, the owner or applicant may apply to the Town Board or the Zoning Board of Appeals for an extension of the original special permit or variance, and the Town Board or the Zoning Board of Appeals may, for good reason shown after due notice and public hearing, extend such special permit or variance for a reasonable period, not to exceed an additional twelve-month period, and may place any reasonable conditions on such extension to secure commencement of construction as promptly as possible. In the event construction on said special permit or variance is not commenced within such twelve-month period, or such period as the same may be have been extended, reapplication must be made to the Town Board or the Zoning Board of Appeals for said special permit or variance.