You only have to replace the PVC if the pipes are damaged. Is your leak coming from 2 pipes that are joined with a threaded connection? If yes, then use some pipe thread compound on the threads. It seals the threads and keeps them lubed for future removal. This compound works better than teflon tape which I've found works better on metal threads. TIghten the nut by hand 'fairly tight', and turn on the water. Turn it tighter by hand until the leak stops. If you've tightedned as far as it'll go, use a wrench to gently tighten 1/4 turn more. Don't do more than that, bkz you'll damage the threads, and then you'll have to replace the pipe.
I haven't used the air jets, but I have used a pipe snake with success. They're like big, fat, floppy gentle drill bits that you turn by hand or with a drill to dislodge debris deep inside a pipe. Use the pipe snake with the trap and as much of the drain dismantled as possible, so you don't have too many bends to navigate.