I have a laptop and the cord that charges it got cut in half and I put it back togther just wondering if it uses more electricity since the wires are no longer insulated.

Insulation does nothing, otherwise we'd have them on our electrical outlets at home to keep electricity from leaking out. It matters in some worlds, but not this one. There were times I had to account for it in a laboratory setting.

What matters is the numbers of strands re-connected and how they were re-connected. If you used solder and all the strands, then it's fine. If you used two of the strands and twisted them together with no solder then not fine because bad connections generate heat and heat is power loss.

Self-fusing electrical tape works wonders, but it might set you back $30 a roll.

Stagger your connections.
You could solder, heat shrink each, then heat shrink both. Or with staggered, and if you don't have small heat shrink, you could probably solder, tape, then heat shrink both(staggered).