We get that your credit cards expire, you update your billing address, or you get a new card. To make sure that you don't see any interruption in the service, please update your card by the Saturday prior to your next delivery.
You can also login and pay for the renewal from your account page:
1) Click 'Subscriptions'
2) Click 'View'
3) Scroll down to 'Related Orders'
4) Here you'll see the 'Pay' button