Watch the Kittens and raise their family.
Maybe spend quality time with there mates. xDDD I know I would if I could. ^^ *HUgs for all*
That makes a lot of sense, especially since after the end of the war many of them had kittens.
What do they do with their mates though?

Sleep all day, play at night XD
yes.
Night adventures are probably amazing!
With Bigwig in the warren, they'll have to absolve owsla-training day and night 
Some poor rabbits won't be getting much of a break

Not everyone is part of the owsla though...

what do the others do?
But I'm sure they just raid farms a lot, and look after each other. 
Farm raids are nice

After that, maybe there is grooming (self and other rabbits).
Interesting...
Dandelion can make up more of them by turning Hazel's and company adventures into El Ahrairah stories.
I think it happened in the book at the end, though it wasn't Dandelion who told that story, IIRC.
I think it was Vilthuril, but I'm not sure...

And if they get bored with storytelling, they can take example from Darkhaven and start fight club, only less deadly. 
That's another possibility. Hopefully they won't take it too seriously though, although just friendly fights might be fun
