Most browsers will send the "referring" page in the HTTP request to get the new page. So assuming your Perl is running in a fairly standard CGI environment, you can get the URL of the referring page by looking at $ENV{HTTP_REFERER} and if defined, put it in a link when you create your page.

(Note spelling of referer, which doesn't look right to me as a Brit, is that the US spelling or is it just a mistake?).