At this point you have a choice. You can continue Week 4 again, so your Week 5 and Week 4 routine is the same, or you can change it up. Either way you're going to change your routine. Your Week 6 routine must be different.

Every four weeks or so you should change your routine. Focus on the same muscles groups, but change the exercise you do. After another four weeks pass, change your routine again (you can go back to your first routine, and just alternate every four weeks). Changing your routine helps strengthen and build muscle without your body getting too used to the same thing.

Start with less reps and sets when doing new exercises and gradually move up. I find 4x4 is a good goal to reach with your reps and sets, but after awhile you'll probably want to increase it as well.

You might have noticed for leg day, when I increased weight, I decreased the sets. This is because your body is going to be working harder with the new weight. After that week you can try and increase your set/reps again.