Twice-told

a twice-told tale

[…] the fact that repetition makes for dullness and that a fresh mind may well be able to introduce a new and hence a more effective approach to what has become rather more than a twice-told tale.

I am aware that the story of “the story within the story” is itself a twice-told tale, but nonetheless I will tell it again, hoping to make it yield some additional meaning—if my initial contention is right.