Mo. Rev. Stat. § 476.540
Any person ceasing to hold office as a judge as defined in section 476.520, for any reason other than death or retirement, may make written application to the commissioner of administration for a refund of his contributions under sections 476.515 to 476.570. On receipt of the written application, the commissioner of administration shall pay the refund in one lump sum which shall equal the total amount of such contributions under sections 476.515 to 476.570. Any person receiving such refund except as provided in section 476.585 thereby waives all rights to retirement compensation under sections 476.515 to 476.570. If such person again becomes a judge of any court covered by sections 476.515 to 476.570, he may restore all amounts previously received as a refund, together with interest as determined by the trustees of the Missouri state retirement system that the contributions would have earned if they had not been previously withdrawn, except that he shall not be required to restore any amounts received pursuant to section 476.585. Upon the restoration, and not otherwise, the prior service as a judge shall be counted toward the twelve years of service necessary to qualify for full retirement compensation.
§ 476.540, RSMo