How do I go back into a form and complete payment

Hello,

I have a person who filled out my form, but not complete the payment portion. How do they go back into their form to complete their payment?  I see how I can click on the "complete submission" button, but how do I actually get their payment??? Do they have to do back and complete a new registration form to pay?

Thank you.

Please note that clicking Complete Submission will not process any payments. It will just move the submission to the completed submissions.

The user will have to make a new submission in order to be able to complete a payment.

If the browser was closed when the user was redirected to make the payment, I am afraid it is not possible to continue making the payment only later.