The commissioner may exempt specific product forms or product lines of a domestic company that is licensed and doing business only in this state from the requirements of Section 425.073 if:
(1) the commissioner has issued an exemption in writing to the company and has not subsequently revoked the exemption in writing; and
(2) the company computes reserves using assumptions and methods used before the operative date of the valuation manual in addition to any requirements established by the commissioner and adopted by rule.