working with forms

I have a forms page that a user will fill out. When it is submitted, it checks to see if any of the field entries entries are empty, and if so, it has a die() statement that has a link (javascript:history.back()) which sends the user back to the form page. However, when they go back to the form page, all the entries they made are erased and they need to redo everything. Is there and easy way to have them go back with all their previously inputted data still filled in? Let me know. Thanks, Matt