Hey, brother. I wouldn't join a church that uses juice. I couldn't take it in good conscience, and I can't imagine a church that would allow people to join who can't participate.
But you ask what I would do if I were a member--I'd find a different church. If necessary, I'd move.
Others may have a different opinion, but that's where my conscience is. The Scriptures enjoin me to drink wine at the Supper--I'm not going to drink something else instead.