Restoration, relocation or reconstruction. If an existing nonconforming use or structure is destroyed, then a permit for its reconstruction may be obtained if such permit application is filed within 90 days of the initial destruction, and reconstruction is completed within 18 months after obtaining said permit. An existing nonconforming use or structure which is damaged but not destroyed can be restored without regard to when the initial damage occurred or when the restoration is completed, so long as the building permit applicant otherwise qualifies for a building permit. Any restoration under this paragraph shall not cause the change or expansion of the nonconforming use. Also, a nonconforming use or structure, when razed or removed from the premises, shall not be relocated on the premises except in conformity with the regulations of the district in which it is then located.