Is there any acceptable way to cover a junction box?
You cannot cover any junction box that still has live wires in it.  Your best bet is to either remove the box all together or just put a cover plate on it. Your other option is to run a new circuit to the new box and de-energize the circuit to the old box and mark the source wires as "NOT IN USE" at your panel in which case I believe you could cover it over. 

If there are live wires in the box, sooner or later you will need to get to the box again, which you can't do if you've covered it over! You'll thank yourself later (as will any future home owner).