Slice up corned beef into about 1/2" wide strips. Place in mixing bowl with drained sauerkraut and mix. Add the whole bottle of Kraft dressing and mix. Add 1 cup of shredded mozzarella and mix once more.
Lay out the crescent roll dough on a baking sheet, to form a rectangle. Press together all the seams. Add corned beef mix down the middle of the crescent roll rectangle. Fold the sides of the crescent roll up, to meet over top of the filling. Sprinkle with mozzarella cheese.
Bake at 375°F for 15 - 20 minutes (make sure the bottom portion of the crescent rolls get cooked, sometimes the time needs to be adjusted) Serve hot, makes great leftovers.