If the glue is dried or no longer present an iron won't do much... Maybe some super glue under the sticker and then let it sit for a few hours to dry would do the trick.
ironing plastic(or anything electronic) is a no no like putting an unwrapped PopTart in the microwave..the stickers on my 8800 and 285 have some edges that aren't to the body, but that's how they put it on and im not messin with it lol