It is the express intent and purpose of this chapter that if a building, structure, sign or land was expanded or extended to the limits of expansion for a nonconforming building, structure, sign or use of land as authorized by a prior zoning regulation or ordinance, no further expansion of said building, structure, sign or land shall be authorized. In the event a nonconforming building, structure, sign or use of land was expanded to a portion of the limits of expansion authorized by a prior zoning regulation or ordinance, additional expansion if permitted by this chapter shall only be authorized to the amount of expansion not previously utilized pursuant to said prior zoning regulation or ordinance.