The SimpsonsThe Simpsons is a satirical parody set in the fictional town of Springfield, and uses many aspects of the human condition including American culture, society, and tv. It follows the middle class family led by Homer Simpson, through all of their adventures.
Yes, they do repeat it sometimes.
When my brothers and I were little (had to be around 1993), we were only allowed to stay up late enough on Sunday nights to watch the Simpsons intro to see the couch. There were some repeats in there.
Go here: http://en.wikipedia.org/wiki/List_of_The_Simpsons_couch_gags
If you run down the list in the "gag" column, you will see "Repeat of [Episode no.] Gag" countless times.
So yeah, the same couch gags have been repeated A LOT.