After you've added a new/correct card on file....
Log in to your personal Donor Dashboard
Select "Recurring" from the menu on the left side
Select the Edit button to the right of the monthly gift
Under Payment Source, choose the correct/new card from the drop-down menu
Select "Save changes"
Please note that if you have chosen to cover the processing fees for your gift that the donation is unable to be transferred to another card/payment method. The existing monthly donation will need to be canceled, and a new gift would need to be created using the new card/payment method. A new monthly gift can be created from the Recurring section in your donor account.