Ind. Code § 8-10-5-10

Sec. 10. The board of directors shall, from time to time after the adoption of said official plan, have the power to modify, amend, or extend the same, provided that upon the making of any such modification, amendment, or extension thereof, the board of directors shall cause notice to be given and shall conduct a hearing, all as provided in section 9 of this chapter, and shall not adopt any modification, amendment, or extension until the notice has been given and the hearing held as herein provided in this chapter.