Due to the fact you are running a bodybuilding program, I assume your goal is to increase size rather than strength. According to the program's Training section, these are the ways to increase overload:
- Lift a greater amount of weight for an equal number of repetitions
- Lift the same amount of weight for more repetitions
- Lift a greater amount of weight for more repetitions
- Decreasing rest periods between sets
- Partial reps
- Negative reps
- Drop Sets
- The cheating method
- The one and half method
- The platoon system
- The flushing method
- The rest pause method
I won't pretend to know what the "cheating", "platoon", or "flushing" methods are. You'll have to look at the links on his page for a better idea.
The general concept of bodybuilding is to push your muscles to exhaustion, but keep cycling through the different muscles so you have enough time to recover the next time you push it. Essentially, you'll want to push yourself each time you are in the gym. Whether it's "1 more rep", or 5 more pounds. Many of the options listed are for when you just aren't able to do the simple whole number increases.
If your training goal is size, this will work. But then so will any high volume program. While you will get stronger, if your goal is to increase your usable strength then you might want a different program that focuses on compound lifts. The key to all this is keeping a detailed journal. You'll need to keep track of the following for each exercise:
- Weight used
- Reps performed
- Rest time (some body builders go so far as to time rest between reps, or time at full contraction and time at full extension)
- External factors (sleep, food, physical labor [including helping someone move])
- Mood (can be used to diagnose fatigue related issues)
You should be keeping a journal anyway, as it helps you figure out why you may be having a hard time, or if you simply want to see what progress you made. If your focus was on strength, most programs don't have any requirements on rest time--so it's not nearly as important to track it.