In one of our applications, we use a look up file (like and excel) where we store these list of predefined Product names. In the beginning it is considerable work to list down all these product names (ofcourse with help from business).
But once done, we store is separately and we also provide an input field in the report where the user can key new products directly into the report (as and when new products are created) and the report updates the excel by the click of a macro enabled button (or if there are limited users you can provide access to the file directly).
Normally the report results are refreshed with new additions after the next refresh. You may also use direct discovery if the user intends to see the updated report results immediately.