Progressive overload. Does it simply mean adding weight to the bar? Progressive overload is what is needed to better your physique and your lifts. When you plateau at a certain weight, you still need to incorporate methods of progressive overload.

You could progressively overload by:
-Reducing rest periods between sets (to an extent).
-Increasing the TUT (time under tension) per repetition by slowing down eccentric phases of any lift.
-Increasing the frequency of the muscle in question per week, assuming the prior volume was not reduced to compensate, meaning overall more volume.
-Increasing volume. Plain and simple. Adding sets to you exercises
-Increasing the repetitions (to an extent). Don't over do this or your pathways may shift towards a different specific goal (1-6 = strength, 10-15 = fast twitch hypertrophy / 15-25 = slow twitch hypertrophy, 20+ = fast twitch aerobic / 30+ = slow twitch aerobic). If you could add another repetition to the same set with the same amount of weight you had a couple of weeks before, you've progressively overloaded.
-And of course, adding more external weight to the lift.

My personal favorite method is to simply add volume.