I think you might be able to draw a parallel with long-running serials like comic books, or even Star Trek itself. They tend to revisit old themes and revolve around a certain status quo.

They tend not to involve multigenerational obedience to an authoritarian regime, though...

The First Fifteen Lives of Harry August. It tells the story of a man who lives his life over and over again. Very interesting story and while not exactly like Garak’s repetitive epic its definitely in the same vein.

I feel like repetitive epic is like a Cardassian version of the dubious literary idea of The Hero's Journey, adapted for the Cardassian heroic ideal of selfless sacrifice to the state. I think Garak would appreciate the "Rememberence of Earth's Past" series (Three Body Problem) for the way that individual heroics take a backseat to the glory and survival of the state.

Unfortunately, not enough detail was given regarding the story or plot, so no comparison can really be made.

I don't know what the most similar novel to The Neverending Sacrifice might be, but I think the exact opposite is probably the 1970s novels satirizing the British Raj called The Flashman Papers. They are incredibly funny, highly offensive, beautiful assaults on the landed gentry, set during one of the most incompetent, badly failed military expeditions to Afghanistan in the history of badly failed military expeditions to Afghanistan--the British one.

No, not the American one with British help--the actual British one, from way back in the seventeenth century.

I love this question. My first thought was not a book, but Béla Tarr's The Turin Horse which depicts the repetitive life of a Hungarian farmer and his daughter. Each day is essentially the same, with similar but ever-changing frustrations, and no hope for change in sight. The audience really feels their frustrations, but the characters also appear to have fully accepted the situation. The title is a reference to the horse-whipping that allegedly drove Nietzsche insane.

Not quite an "epic" in the usual sense, but absolutely repetitive and a surrender to economic powers beyond one's control.

I always got “Groundhog Day with Guns,” plus “Waiting for Godot,” plus Game of Thrones.

Too much alliteration?

The closest I can think of--at least as far as multi-generation epics--would be Wilbur Smith novels.