If you have a PayPal account, you can do it there. If you don't have a PayPal account, then wait until it expires, then next time you sign in, you will be directed to a renewal screen where you can enter the new card details. If the card you had used for the recurring payments hasn't expired, but you want to change it anyway, cancel the recurring payments (from your Accounts page, which you access from the drop-down menu under your username at top right). Then your membership will expire and you can renew with the new card.
And don't worry, nothing happens to your books data if your membership expires. We only delete a member's records if they specifically ask us to.