No structure on lands containing a legal nonconforming use may be extended, enlarged, totally rebuilt, substituted, moved, remodeled, modified, or added to except when required to do so by law or until the legal nonconforming use has been made to conform to this chapter. This subsection does not apply, however, to structural repairs or alterations that are made in strict compliance with § 62.23(7)(h), Wis. Stats., including such amendments as may be made thereto from time to time.