yes use dionysus as an example. he lost in the cup and didnt make it 2 playoffs but since he won B3 in season 19 he was still in B3 4 season 20.
He won it in 18. Which actually makes it a better example (it's not just win B3 and you enter again the following season, it must be entry for every season).
Perfect example is Sharman Globetrotters: they won B3 once in season 10 and have taken part every season since, even though in seasons 14, 15 and 19 they didn't win either domestic competition:
http://www.buzzerbeater.com/team/53418/history.aspx