How can a person submitting a form re-read an earlier submission?

By default the person submitting a form cannot re-read earlier submissions, if you want them to access earlier submissions and edit them you can send them a link that allows them to access the data they posted previously and update it.

Kindly refer to this guide

http://www.jotform.com/help/40-How-to-Let-Users-Update-Their-Form-Submissions-at-a-Later-Date

Another approach is to list all reports withing the HTML field in your form by creating a visual report and setting it as an HTML listing

http://www.jotform.com/help/187-How-to-create-a-Visual-Report-with-your-Form-Submissions

If you need further clarifications and detailed instruction please let us know.