Billboard, wall, roof and ground advertising signs shall be limited to the number in existence at the time of the passage of this section, and may be replaced or relocated in permitted districts within one year after the billboard, wall, roof or ground sign is destroyed or removed from the original location. The replacement or relocated billboard, wall, roof or ground advertising sign shall not exceed in size the total square footage of the billboard(s), wall sign(s), roof or ground advertising signs that same is replacing, and shall be subject to all other provisions of the district in which same is to be located.