If it was running right with a dirty K&N, then you probably don't have to rejet. K&Ns, when clean, flow more than a UNI, so theoretically you should have to re-jet just a tad when you change air filters.
One way to tell usually if your air filter is clogged, if you jetted the bike with the clean filter (like you're supposed to) and it's the same temp and such outside as when you last jetted, if the bike idled fine when you jetted and now it doesn't, clean the air filter!!! Don't just turn up the idle and think it's fine.