Whenever premiums are not waived under section 1912 of this title solely because the insured died prior to the continuance of total disability for six months, and proof of such facts, satisfactory to the Secretary, is filed by the beneficiary with the Department within one year after the insured’s death, the insurance shall be deemed to be in force at the date of the death, and the unpaid premiums shall become a lien against the proceeds of the insurance. If the beneficiary is insane or a minor, proof of such facts may be filed within one year after removal of such legal disability.