If you have stopped making progress and can’t even seem to work out hard enough to get sore the next day then perhaps its time to try forced negatives. Don’t overuse these! These put a lot of strain on your joints and tendons so if you do these often you will probably suffer from overuse injuries. In forced negatives you use more weight than you can lift so either a workout partner or your other hand needs to help get the weight up then you lower the weight slowly under your own power. Here are some examples of how you can do forced negatives.
Lats: When doing pullups, put a weight belt on and hang a dumbbell from the belt so you are lifting about 10% more weight than you normally use for pullups. Use a chair to get yourself into the up position, then lower yourself slowly and repeat. Killer!
Biceps: watch this video to see how to do forced negatives on biceps. You take your normal dumbbell weight and add about 20%, now there is no way you can do a curl with it so you help the dumbbell up using your other hand. When you get the dumbbell to the top you let go with your assisting hand and try to lower the dumbbell slowly. Repeat this for 8 reps, its killer!
Chest: Forced negatives for the chest are much easier to do with machines than with free weights. First you could do this using pushups. Do a normal pushup to the up position. Put on hand behind your back and slowly lower yourself to the ground one handed. Use both arms to push yourself up again and put the other hand behind your back and once again lower yourself slowly to the down position. Repeat for as many reps as you can.