Return the pork to the casserole. Add the demiglace, water, thyme, parsley, bay leaves and peppercorns and bring to a simmer. Cover and bake for about 4 hours, or until the meat is fork-tender and the juices are reduced to 1 cup. Transfer the pork to a plate and refrigerate until cool, about 1 hour. Strain the pan juices and skim off the fat. Boil the juices until reduced to 1/2 cup, about 10 minutes. Cover and refrigerate.