I feel your pain! Crickets drive me crazy. We used to have them in our house growing up, I would hunt them down until I found them.
I always just listened and followed the noise, carrying a shoe to smash it with of course.
If you can't see it, maybe track it down as best you can and spray the area with an insect killer?
Good luck - I have shivers now just thinking of crickets, I hate those darn things. I had a cricket up the leg of my pants once, ooohh, ick, I have to stop talking about this now!
tamie