Any public officer or employee receiving leave of absence under sections 192.26 to 192.264 and having rights in any state, municipal, or other public pension, retirement, or relief system shall retain all such rights accrued up to the time of taking such leave, and shall have all rights subsequently accruing under such system as if actually employed during the time of such leave; provided, that so far as any increase in the amount of money benefits accruing with respect to the time of such leave is dependent upon the payment of any contributions or assessments, the right to such increase shall be conditioned upon the payment of such contributions or assessments within such reasonable time after the termination of such leave and upon such terms as the authorities in charge of such system may prescribe.