If some of the NaOH in your lye solution has precipitated due to it being too cold, you have to warm the solution in a hot water bath, break up the sheet of precipitated NaOH, and get the bits of solid NaOH to dissolve again.
A person can add additional water to speed the process of re-dissolving the NaOH, but if you do that, you will reduce the NaOH concentration, so you will have to keep track of the amount of water added, ensure you don't add more water than makes sense for your soap making, and recalculate the lye solution concentration you end up with.