Section 139. Any life company may, at the request of the holder thereof, exchange, alter or convert any policy of life or endowment insurance or annuity contract issued by it or a company that is admitted and authorized under this chapter and is an affiliate of it, as defined in section two hundred and six, hereinafter called the original policy, for or into any policy of life or endowment insurance, hereinafter called the rewritten policy, as of the date of the most recently issued original policy or as of the current date, or as of any intermediate date, conforming with the laws in force as of the date of issue which the rewritten policy bears; provided, that, if the rewritten policy bears a date prior to the date of application for exchange, alteration or conversion, the amount of insurance under the rewritten policy shall not exceed the greater of (a) the amount of insurance under the original policy or policies if of life or endowment insurance, or (b) the amount of insurance which the premium paid for the original policy or policies would have purchased if the rewritten policy had been originally issued as of the date of issue it bears. Nothing in section one hundred and twenty shall be construed to prohibit the exchange, alteration or conversion of a policy of life or endowment insurance or annuity contract under this section, and sections one hundred and twenty-three and one hundred and thirty shall not apply to a rewritten policy issued under the authority of this section, except that section one hundred and twenty-three shall apply if the original policy is an annuity contract. Nothing in section one hundred and thirty-one or section one hundred and thirty-two shall be construed to prohibit making the application for the original policy, if one of life or endowment insurance, or the application for the rewritten policy issued under authority of this section, or both such applications, a part of the rewritten policy, by endorsing thereon or attaching thereto a copy of either or both such applications. Nothing in said section one hundred and thirty-two shall be construed to prohibit the incorporation, by a rider or endorsement or otherwise, in a rewritten policy issued under authority of this section and bearing a then current date or an intermediate date of a stipulation making the incontestable provision required by said section one hundred and thirty-two operative from the date of issue of the most recently issued original policy, if one of life or endowment insurance.