Već sam jednom bio-la na programu, da li mogu ponovo da idem?

Da, ukoliko si se vratio-la u zemlju pre isteka J-1 vize i nastavio-la da redovno polažeš ispite.

I’ve been to the program once before, can I go again?

Yes, if you returned to the country before your J-1 visa expired and continued to take exams regularly.