Can I light a cigar again after it has gone out?

The quick answer to this question is, yes. But, of course, there are some exceptions.

About 15 minutes after the embers have gone out represents a turning point. So what happens? Why should you refrain from lighting up again? When tobacco burns, the different substances contained therein are activated. When a cigar goes out from not drawing on it, these substances settle back into the cigar and penetrate the tobacco. If you light up the cigar again after a certain amount of time has elapsed, the taste will have been adulterated and will not be pleasant.

To re-light a cigar, completely remove any ash from the end beforehand. Otherwise, it will be difficult to get it to ignite properly. Once the cigar had cooled down, the ash should fall off easily.