Any policy dividends hereafter declared, or reduction in rate of premiums hereafter made or continued for the first or any subsequent year of insurance, under any policy of group life insurance heretofore or hereafter issued to any policyholder may be applied to reduce the policyholder’s part of the cost of such insurance, except that if the aggregate dividends or refunds or credits under such group policy and any other group policy or contract issued to the policyholder exceed the aggregate contributions of the policyholder toward the cost of the coverages, such excess shall be applied by the policyholder for the sole benefit of insured individuals.