Much of re-training aggressive dogs successfully is the ability to see the dog, make accurate, educated assumptions based on observation and experience as to what the dog is thinking or what his motivation is, and addressing what is seen. The Chow must have solid obedience skills so that the dog can be given an acceptable alternative to aggressive behavior. Call it whatever you want, but if the dog doesn't have obedience skills, they need to be safely taught. However, there is a difference between a reward and a bribe and in the long run, which one you use does make a difference. There is nothing to be gained from letting the dog practice aggression.
Patience is a virtue - a necessary one.
The problem probably didn't start overnight and likely won't go away overnight. There is no magic wand that will fix an aggression problem nearly as quickly as everyone would like. Working with an aggressive dog requires planning and forethought. There will be situations it is best to avoid - sometimes for the short term, sometimes for the long term. And sometimes it is necessary to compromise.