What is the solution to the danger of being complacent after a successful project or a very profitable year?

Set higher targets
Easy targets are not really targets at all.
Aim to be the best in your industry for quality and service.
By aiming for what seems impossible, people often actually do it!

Identify opportunities for improvement
Be sure all employees learn lessons about what should be improved so they can deliver something better the next time.

Do not avoid competition
Avoiding competition may seem beneficial at first but will hurt in the long run. With only a few competitors, a company can easily become satisfied with its performance. When that kind of complacency sets in, it eventually downgrades the role the company will play in the market.

A certain amount of risk
A calculated risk engenders a sense of urgency and keeps everyone alert!

Pressure from outside the company will force people to change and make progress.

Source: The Ghosn Factor, Miguel Rivas-Micoud, McGraw-Hill