Hi
Contact your card issuer for instructions.
When a replacement payment card is issued:
Some card issuers may automatically associate your new card with the existing Device Account Number (created when your original card was added to your device), replacing the old card. This leaves you free to continue using the same card account via Apple Pay without needing to do anything yourself.
Other issuers may require you to remove your old card from Apple Pay and add the replacement as a new card.
Contact your card issuer to ask whether you need to take any action.