How do stand-up comedians deal with joke repetition?

Yes, teaching. My last assignment was teaching Transportation of Hazardous Materials to DoD and related contractors. Two week course, a legal requirement based on content (a full 80 hours) and 4 college credits toward a degree. You had to pass to certify HazMat shipments. And repeat every two years. We gave the course 17 to 18 times a year, home in Hawaii and on the road throughout the Pacific. We worked as partners and tried to liven up the lecture as much as possible with humor - 300 to 600 page regulations; Air, Sea, Land - US and some international differences thrown in. I enjoyed the creative parts to keep the students attention. I would have kept it up but our supervisor was …… so I retired.

That reminds me of the day I had to go to Traffic School to “work off” the only moving violation I’ve ever received - the outfit that ran the class was called “Laugh and Learn.” I suspect most such classes are similarly staffed by folks trying to earn a living as comedians. I remember admiring the guy for keeping such a chipper countenance while delivering his routine for what must have been the thousandth time.

The humor was tepid, but it was perfect for a situation in which “none of us want to be here so let’s try to make the best of it.”

As a retired teacher I’ll chime in on the point that keeping well-worn material fresh is quite do-able, but you have to have your heart in it. When you do, everybody wins.

Back in my college days I had to do a lot of driving. And since I was a crazy kid, I racked up a lot of tickets. In the days before everything was in the big central computer in the sky. So I got to go to traffic school … a lot. The one near college was taught by a policeman from a neighboring city. It got to the point he’d say “Hi LSL!” when I walked in.

He had a real knack for being easy going and friendly, making dry material into relatable learning. And yeah, pretty soon I’d heard all his jokes. He had a comeback for anything. Why? because the public isn’t that creative, so he’d heard just about every fuss or whine a time or 3. As had I.

Curt Smith from Tears for Fears had an interesting perspective on how he can play the same material for decades:

A lot of people presume, “God, you must be sick of singing ‘Everybody Wants to Rule the World.’ You’ve been doing it for four decades, man.” No, not at all. Because as soon as we hit those first four notes, the whole emotion of the audience changes completely. All thanks to four simple notes of music. Then suddenly your mood changes and you enjoy singing it even more. I wouldn’t choose to listen to “Everybody Wants to Rule the World” if I’m at home by myself; I’ve heard it too many times. But playing it live, it’s the most enjoyable thing to sing because of this two-way between you and the audience. It’s the same for “Mad World.”

From this interview: Curt Smith Answers Every Question We Have About Psych

Please tell me that you used to make this announcement over the PA before your flights.

When people would express surprise that I’d switched to teaching, I’d explain that it’s just doing standup and improv and a talk show all at the same time: “And that’s why it’s so exhausting.”

“Hey, I’m getting paid to insult students… and vice-versa, of course.”
Getting to know the kids made playing off their personalities much easier.

Comedians live for the laugh. It’s not the sort of profession you would choose if you did not love writing and telling jokes many times.

Yes; since writing the OP, I’ve pondered this difference in personality types. I have a friend who prides himself on remembering and performing those ‘shaggy dog story’ jokes in the pub. And one of my brothers is a prolific creator of puns, and again - proud to recite them. It’s just a different quirk that personally, I only really like ephemeral, one-time gags.