If the board of chosen freeholders shall find the petition to be in proper form and signed by the required number of legal voters of the county, it shall determine what law for the establishment of a county park system or county park commission applicable to the county shall be submitted at the referendum requested, and the fact that the provisions of any law may have been submitted and rejected at a previous referendum shall not prevent the board from again submitting that law. Not later than forty-five days preceding the next general election, the board of freeholders shall certify to the county clerk the question to be submitted to the voters of the county.