Although Sharpie brand permanent markers are relatively inexpensive, it can be a pain to go out and get a new one if the marker happens to dry up in the middle of writing something and you need to finish your task. Sharpie markers cannot be refreshed indefinitely, but you can stretch the ink a little further with the aid of rubbing alcohol.
Dip the dried tip of the Sharpie into rubbing alcohol and hold the marker in the alcohol until the tip is fully saturated. This will likely take 30 to 45 seconds.
Cap the marker and stand it upright for several minutes.
Test the marker on a sheet of paper. If the line the Sharpie draws is not bold enough, dip the marker back in the rubbing alcohol, cap it again and let stand for several minutes.