You can try heating the areas around the decal this may be enough to pull it tight, keep the nozzle pointed away from the decal as much as possible. You can also use an iron to shrink the covering. Turn the iron to a higher setting and keep it moving.
I personally would try using the iron 1st and you can iron right up to the decal. If your careful you can use the iron to shrink the covering without the iron even contacting the film.
Good Luck!!
Anthony