Add the remaining peppers and onions, cover, and cook on HIGH for 3-4 hours. Remove chicken and cut/shred into slices (chicken left longer will tend to shred more – cook to your preference). Return the sliced chicken to the slow cooker to marinate in the juices for about 10 more minutes (on LOW) until ready to serve. If you find that there is too much liquid, you can remove till there is a desired amount before serving.