Sorry I don't understand. As long as I can see your script runs fine. To allow users generating multiple orders you should change the user interface, not the script behind

If this is what you want, I think that a couple of button "Add to your order" and "process order" in the response page could do the trick.

The first button could resend the first page with a hidden field containing a serialized version of the order so far (this is a shortcut, better way would be mantaining a session server-side with the content of the user "cart").

The second button would confirm the order as entered (sum of all the single entry)

PS. Remember to be careful using serialized data in a HTML page. The most obvious way of serialize through Data::Dumper and deserialize with eval open the road to code injection when used on the internet! You should always be aware that anybody can put anything in your hidden fields, and avoid the possibility of exploitation