Whenever a nonconforming use of land or of a building in any district is changed to a conforming use or abandoned for a continuous period of six months or more, such use shall not thereafter be reestablished, and any subsequent use of the premises shall be in conformity with all the regulations of this title. The provisions of this section shall not apply to dwellings in the A district that are nonconforming solely because they were not subject to site development review pursuant to Section 17.06.090 of this title. (Prior gen. code § 8-62.8)