Carl, it is sad to say but my past experience's with praise and worship bands is that most, if not all of the members claim they don't have the time to practice as to take it to the next level as you call it. However in many case's it is probably true with there families and jobs.
I would take the time each week to really get familar with each song to the point I didnt need sheet music in front of me most of the time. I was always at practice and set up ready to go on time. I always did my best to do my best and stay fully committed even if most of the others were not. I would ask myself questions like, why should I practice these songs when no one else does? Why should I care would no one else does? Why do I bust my hump to get here on time when I know we are going to start late? I was always turning to God with why, why, why.
Actually this band wasnt all that bad but I wanted that next level just as you do and I just didn't see the members of this band ever making that committment. Finally in God's own time He delivered me and gave me the opportunity to be part of a next level praise and worship band.
So don't let the others discourage your passion to reach that next level. Pray on it and when the time is right God will place you with the musicians that want to reach that next level just like you.
Now I only play as a fill in bassist, and that is when the regular bassist cant make it but this prasie and worship band strives for that next level. Everyone shows up for rehearsal on time and prepared and what a difference it makes.
So just hang in there Carl, Pray, and let God do His work.

Dave