It seems when I sit down to practice lead, the blues is what come out. I don't know your setup for practicing over recorded tracks, but if its a poor mans like mine (cd player), I recommend checking out these "band in pocket" instrumental cds. I picked up the blues cd which has 10 or so tracks on different keys which are all cool blues tunes with no lead guitar, I tell ya, for me, this cd enabled me to really practice. I couldn't believe the stuff I could play when I had a blues band behind me (some stuff sounded better then others, thats for sure, lolololo!).
The tracks are long, so you can just keep working out the wrong notes. One thing for me though, I try to play something different on each track, incorporating the stuff I liked and worked out previuosly. Yea, check out the instrumental cds, they are, for me, a big help.