You need to go to your temporary internet files.
From the IExp menu bar, choose Tools, Internet options, "general". Click on "delete files" (not delete cookies) which deletes a large number of files you don't really need and then click "settings" and "view files". This brings up a list of cookies - I think you can leave this open so you dn't need to faff about each time. Then you need to look through the list and delete anything with the paper's web address in it. then you can reload the voting page and vote again. Go back to the window you left open, click on View and Refresh and the newspaper's cookies will be back - delete them again etc etc.
But it is, of course, cheating