Any contract of insurance issued by a stock company or mutual association against liability arising under this chapter may be canceled by either the employer or the insurance carrier within the time limited by such contract for its expiration.
No such policy shall be deemed to be canceled until:
The provisions "b" and "c" of this section shall not apply where the employer has replaced the contract to be canceled by other insurance, and notice of such replacement has been filed with the Commissioner of Banking and Insurance. In such event the notice required by provision "a" may, if given by the insurance carrier, recite as the termination date the effective date of the other insurance, and the contract shall be terminated retroactively as of that date. No notice of cancellation of any such contract need be filed in the office of the Commissioner of Banking and Insurance where the employer is not required by any law of this State to effect such insurance.
N.J.S. § 34:15-81