If you have purchased a package, it is through Universal Vacations, which is a
travel agency. If you want to just get APs you can upgrade to them with your tickets that you get with your package once you get to the park. Then you can use that for restaurant and merchandise discounts but not for a room discount since that was previously booked with your package.
You really have to read the fine print when you get a package. Any changes are always done at a fee. If you are still far enough out, you may be able to cancel completely without a fee and then just start again by ordering APs and booking your room with an AP discount (if available) separately.
To see if it is worth it, you can check AP rates (if available) by entering the code APH when you use this link
http://www.loewshotels.com/en/booking/uo?hotel=UEPBH,UEHRH,UERPR