A redevelopment plan which has not been approved by the governing body when submitted by a redeveloper under section 18-2155 or when recommended by the authority may again be submitted or recommended to the governing body with any modifications deemed advisable. A redevelopment plan may be modified at any time by the authority, except that if modified after the lease or sale of real property in the redevelopment project area, the modification must be consented to by the redeveloper or redevelopers of such real property or his or her successor, or their successors, in interest affected by the proposed modification. Where the proposed modification will substantially change the redevelopment plan as previously approved by the governing body the modification must similarly be approved by the governing body.