For most applications the concentration isn't that important, and I bet in that procedure of yours the NaOH is only used to basify something and the amount isn't critical. In that case prepare a nearly saturated solution and use that instead.
If you really need exact concentrations then buy some new NaOH, it's not that expensive. Use the wet NaOH for "everyday" basifications, to clean your toilet, unclog your sinks, disposing of dead bodies etc.