Best way for user to change information

I have a registration form embedded in my website. What is the best way for the user to change or add information after the form is submitted?

I have written script that runs after they enter their email address which checks to see if there is an existing record with a matching email. If found it copies the data from the existing record to the input fields. This works fine except for file upload fields, URL fields and of course the new subforms data.

Herb Wexler