Lengthen Existing Wire Without Junction Box

When we built our house a few years ago the electrician ran a wire to a junction box in our basement ceiling because we thought we were going to want a floor outlet in the living room on the main level. We haven't needed it because of the way our furniture is arranged currently but may still want it in the future. I am currently finishing my basement and want to move the junction box, mentioned above, from an area that will be finished to an unfinished area. Unfortunately the wire is not long enough to reach the unfinished area. Is there an NEC approved way to lengthen wire without having it in an accessible junction box? I really don't want a random blank faceplate in my basement ceiling. Thanks for your help.