(1) After every five years from the date of coming into operation of the finally prepared Regional Plan, the Board shall review such Regional Plan in its entirety and may, after such review, substitute it by a fresh Regional Plan or may make such modifications or alterations therein as may be found by it to be necessary.
     (2) Where it is proposed to substitute a fresh Regional Plan in place of the Regional Plan which was previously finally prepared or where it is proposed to make any modifications or alterations in the finally prepared Regional Plan, such fresh Plan or, as the case may be, modifications or alterations, shall be published and dealt with in the same manner as if it were the Regional Plan referred to in sections 12 and 13 or as if they were the modifications or alterations in the Regional Plan made under section 14.