Damage or destruction. Should any such structure, other than a sign, be destroyed by any means to an extent of more than 75% of its replacement cost at time of destruction, it shall not be reconstructed except in conformity with the provisions of this chapter. In the event that such damage or destruction is 75% or less than the replacement cost of the structure, repairs or reconstruction may be undertaken, provided that such restoration is started within 12 months of the date of destruction.