Except for a dwelling which may be replaced in whole or in part, if a nonconforming building, structure or land use activity, or part thereof, has been partially or totally destroyed or damaged by any cause it may be rebuilt or restored as a nonconforming building, structure or land use only if reconstructed or restored in compliance with the New York State Uniform Fire Prevention and Building Code, with the same, or an improved, general site layout as that of the original structure. Zoning Board of Appeals approval of reconstruction or restoration plans shall be required and the Board may impose conditions on such approval if such conditions would improve an otherwise undesirable situation and bring the nonconforming use or activity more into conformity with the regulations for the district in which it is located. Application for Zoning Board of Appeals approval for reconstruction or restoration shall be made within 12 months from the date of damage or destruction and work commenced within six months and completed within 18 months from the date of Board approval. Failure to meet these time limits shall terminate the nonconforming use, except that a six-month time extension to any of the time limits may be granted by the Zoning Board of Appeals.