Platueaus are inevitable, we all know that. Just work through it and alter your program to, hopefully, reap more benefits. At times it helps to just choose a program straight from some fitness guru and do that for 2-3 weeks. It will usually lead to either slight overtraining (causing an adaption) or slight undertraining (allowing you to recuperate from possible overtraining).
Personally I like to mix rep ranges because unless I lift heavy (3 reps or less) on a regular basis I just don't look the same. There's some element missing. That said, recent research tends to advocate longer TUT for hypertrophy so that generally means medium-rep sets (say, 8-9).