A marketing order shall not be submitted for reapproval until one year after the original enactment, or within one year of any prior approval. However, if no provision is made in any marketing order for reapproval or for termination in less than five years, the director shall at least once each five years hold a hearing, duly noticed and held in accordance with the provisions of this chapter. If the director finds after the hearing that a substantial question exists as to whether such marketing order is contrary to, or does not effectuate the declared purposes or provisions of this chapter within the standards and subject to the limitations and restrictions which are imposed in this chapter, such marketing order shall be submitted for reapproval. The vote for reapproval shall be the same as used for original approval of a marketing order. The director shall determine whether such approval shall be by assent or referendum. An amendment to a marketing order which extends the term thereof shall be deemed a reapproval of the marketing order. A marketing order which within five years prior to the effective date of this act has been amended to fix or extend its term shall be deemed to have been duly reapproved.