If an exchange has a surplus of admitted assets over all liabilities in a sum equal to 11/2times the minimum paid-in capital required of incorporated insurers issuing policies on a reserve basis and doing the same classes of insurance, then the Insurance Commissioner, upon written request, shall issue his certificate stating such fact. Subscribers at an exchange so certified shall have no liability for assessment on policies issued while such certificate remains in effect. Whenever the commissioner finds such fact does not exist, he shall revoke and require the surrender of his certificate. Upon revocation of such certificate no policy shall thereafter be issued nor be permitted to remain in force beyond the date fixed for the next payment of premium without written endorsement thereon providing for assessment liability in accordance with the terms of this chapter.