Ah, in that case my method wouldn't work. We have a feature request to run payment authentication while the form is open, but it hasn't been addressed yet. You could try to take in the user's email address and, if the payment failed, run a workflow that emails them to try the payment again. You could pre-populate the form with most/all of the initial information and embed that into the URL so the public user would get most of their form back. 

We are emailing the success (tx id) and unsuccessful payment to the end user. The scenario we have is summer school and users are trying to pay for courses. We have had issues of forms/workflow being slow hence people paid for seats that were full and refund was issued (as db was not reflecting the accurate number of seats available). We are trying to change the design by using a web service to reserve the seat and then asking for payment. The issue is that if payment fails then the person has a seat without paying (which eventually we have to write more logic to release). If the payment confirmation was on screen it would give the person a seat and take payment at the same time. There was one vendor at the empower conference 2019 which provided that capability but it is not available with braintree.