There is a transit sign at DPS, but I have never used it. Technically, they do have transiting flights (QF comes to mind), but it is Indonesia and it wouldn't surprise me too much if they will make you pass customs so that they can collect the exit tax. Think it's up to 75000 rupiah now. But though customs is on Balinese time (read: slow), you should be able to make it even if you have to go through.