Mo. Rev. Stat. § 376.696

Any other law to the contrary notwithstanding, no contract shall be entered into by the governing body of any political subdivision to purchase any insurance policy or policies unless the contract is submitted to competitive bidding at least every six years and the contract is awarded to the lowest or best bidder. The renewal of any insurance policy during any period between submissions of the contract to competitive bidding shall not constitute a separate and distinct contract for the time covered by the renewal but shall be treated only as an extension of an existing contract.