By endorsement or rider approved by the commissioner and sent to the policyholder, a reciprocal insurer may simultaneously with or after the adoption of a plan of conversion amend an outstanding insurance policy for the purpose of extinguishing a right of the holder of the policy to share in the surplus of the reciprocal insurer. This amendment shall be void if the plan of conversion is not submitted to the commissioner or, if submitted, is disapproved by the commissioner or, if approved by the commissioner, is not approved by the eligible subscribers on or before the first anniversary of its approval by the commissioner.