When an ENC (cell) that you hold is 'cancelled' by the ENC producer nation and replaced by a new ENC (cell), your AVCS licence will be automatically updated to include the new ENC (cell) and you will be sent a new set of Chart Permits.
An ENC can be 'withdrawn' from AVCS for safety reasons. In that case, the permit remains in permit file, and there is no automatic replacement. You should manually remove the ENC from your ECDIS until you are informed that it is safe to re-install.
If you have not received new Chart Permits or you are unsure if ENCs have been cancelled or replaced then contact your ADMIRALTY Chart Agent for advice.