In medium skillet over medium-high heat, heat pork and jus, breaking up meat with spoon, 5 to 7 minutes or until pork is shredded and liquid is reduced by half.
In small saucepan over medium heat, combine 1/3 cup remaining jus from skillet and refried beans. Season with cumin and chili powder. Cook 3 to 4 minutes, stirring occasionally, until bean mixture is thoroughly heated.
Divide bean mixture and pork evenly among tostada shells. Serve with suggested toppings.