Many feel intimidated when facing a high lip and will do all kinds of weird things with their swing to try to get the ball to come over the lip. Keep it simple, by estimating what the angle is from the ball to the top of the lip. The next question is what is the angle on your wedge?
If the angle of your wedge is more than the angle of the slope, make a neutral swing because the loft of the club will hit the ball above the angle of the slope.
Trust the club to do the work and it will easily pitch the ball over the lip.