If you need to update a card manually (over the phone, etc) Spiffy makes this easy to do on any Order, Subscription, or Payment Plan.

Navigate to your customer’s Order, Subscription, or Payment Plan record and locate the Payment Details section click on the card details and select + Add Card.

This will change the card on file to the new one, any scheduled auto-retries on failed payments will attempt to use the new card. Any manual retries would also attempt to charge the new card.