Hi Satas,
Like everyone said.......sure you can change your bag. That's the benefit of a 2-piece system........if your bag springs a leak....or your dog's nail catches it and causes it to leak.......you can just replace it without doing a full barrier change. If the bag is intact and just smells bad then you can put a new bag on, and you can clean the old bag and save it for another day, or as a backup in case your supplies don't arrive on time. Normally when you order ostomy supplies you order the correct number of bags for the number of barriers. But keeping a few bags on hand in case a few don't last as long as you expect is a really good idea. Having a new barrier to install and no bag really sucks.
So just use a good dishwashing soap, like Dawn, to thoroughly clean the bag, blot with a paper towel, and then let air dry. You'll find they last a good long time, and if you're a cheapskate, or have to buy your own supplies without the help of medical insurance.....this is one way to lower your cost.
;O)