If you registered with a download plan at a previous rate, your account will continue to renew at the original rate, provided your account does not lapse.
If the card on file becomes outdated, the account will automatically move into a cancelled state (your menus will remain saved). The account can be renewed at any time, though it will be necessary to renew at the current rate.
To prevent a lapse in service, update the credit card on file through My Account (as shown below). Click edit next to Billing Information to enter updated payment information.