Go real heavy once every second, third or fourth week.
Meaning, you would do 3 or 4 sets where you try get the new PB, then the following weeks, you back off the weight, perhaps 20-30 kgs at least. Stick with triples and doubles on these workouts as well, and 3-5 sets.
Eg:
Week1
Heavy (all out)
Week2
Light (80 kg off the heavy week)
Week3
Moderate (40 kg off the heavy)
Then go for week 1 again, or do a week4, where you do another Moderate session, 30-40 kg under what you lifted at during your all out week.
This, of course, if you're lifting doubles and triples for the most part.
-Hedge