Phrasing

Question about phrasing: I often find when playing to jam tracks that my phrasing is becoming too regular - everything starts on the first beat, lasts two bars, then there's a pause, repeat the lick for two bars, etc., etc. I think partly it's a consequence of concentrating on using chorus forms and partly from having a limited lick vocabulary. I don't mind that too much because I know it's just an inevitable stage in learning - you pick up a structure and apply it too rigidly at first - but it's still frustrating. Any tips on how to break out of a rut when you find yourself playing the same old thing over a jam track?