You can easily make changes to your payment info in the Billing section of your Infura Dashboard.
Update Your Credit Card
If you wish to change your credit card information, see the following steps.
Go to your payment details by clicking Settings > Billing, in the upper right-hand corner.
Under 'Payment Info,' click the 'Edit' button.
Update your credit card information (card number, expiry, cvc), and click 'Save Card' when you're done.
All set! Any next invoices will be paid directly with the new credit card details you've just set.