If you receive a warning from PayPal that your card is about to run out you need to enter the details of your new card.
To add your new card:
1. Log in to your PayPal account.
2. Click the Profile
button at the top right of the page. (Gray head in a gray box!).
3. Click "Profile and Settings".
4. On the left click My Money
5. Click Update
Debit and credit cards
6. Select the card from the list, and then click Update
To pay by direct debit and avoid this problem do as above, but click the Add Bank Account
If your card has already run out and the subscription cancelled just click the "Subscribe" link again (left menu and other places). You can then choose a different method of payment such as Direct Debit if you wish.
** Note that the PayPal direct debit is not a "proper" direct debit "contract" that can be cancelled from the bank end. For that you need to set up a direct debit with GoCardless. See the FAQ "How do I pay by Direct Debit?