This is obviously only part of your code as the form elements are not all here.

You don't necessarily need to get into AJAX if you don't want to.

All the php code in your page is going to get parsed each time the page is loaded.

If you have the 'action' attribute of the form element set to '' then each time the form is submitted, the page will reload.

What you have to control is which bits of information are 'sticky', that is held over from the previous parsing of the form and which bits of information are new based on certain values passed when the form was submitted.