Any variance permit shall become void at the expiration of one year from its date unless the premises affected thereby shall have been used or occupied in conformity with such permit by that time, or unless the Planning Commission determines that the criteria of this Chapter would best be served by a different expiration date designated in the approval or conditional approval; provided, however, that such time may be extended by the Planning Commission after application by at least one of the owners of the premises involved or by a duly authorized representative, and after notice and hearing thereon as provided in this Chapter for the hearing of the original application, and on a showing of good cause for such extension. (Ord. 89-1 § 1, 1989.)