Well, it depends on how your pages are setup, if pages are exactly the same whether people logged in or not, you don't need to make any changes to them.

If you have say a menu that only appears when you're logged in, and appears on every page when you're logged in, you don't need to create new versions of every page, just edit the existing pages and add something like

PHP: Select all

if(//logged in)
{include('loggedInMenu.php');}