All contractual provisions contained in a collective bargaining agreement entered into pursuant to the provisions of this chapter shall continue in the following collective bargaining agreement unless either the bargaining agent or the corporate authority shall, in writing, within the thirty-day (30) period referred to in § 28-9.1-7, propose a change in any contractual provision. The parties may agree in writing to continue all contractual provisions contained in a collective bargaining agreement until such time as the parties enter into, and have ratified or arbitrated, a successor agreement.