You should try to find where those wires go to and replace them, especially since you have got them exposed this far. Perhaps to an outlet on the second floor?. An ohm meter and a long piece of extra wire can allow you to determine the opposite end of those wires. If you get this far, simply tape new wire to the old wire and use the old wire to "pull" the new wire in place. (assuming its not stapled inside the wall). If it is stapled inside the wall, you still should be able to get a fishtape from point A to point B. Simply pull new wire and abandon the old.