Thirty-Six Stratagems
Keep different plans operating in an overall scheme; if any one strategy fails, apply the next strategy.

If all else fails, retreat (走為上策, Zǒu wéi shàng cè): If it becomes obvious that one's current course of action will lead to defeat, retreat and regroup. When one's side is losing, three choices remain: surrender, compromise, or escape. Surrender is complete defeat, compromise is half defeat, but escape is not defeat. As long as one is not defeated, there is still a chance.  This is the most famous of the stratagems and is immortalized in the form of a Chinese idiom: "Of the Thirty-Six Stratagems, fleeing is best" (三十六計，走為上計, Sānshíliù jì, zǒu wéi shàng jì).

See also: The Art of War
The Book of Five Rings
On War
Cognitive dissonance
Psychological warfare

References: 

Sources: The 36 Secret Strategies of the Martial Arts: The Classic Chinese Guide for Success in War, Business and Life by Hiroshi Moriya, William Scott Wilson
The Book of Stratagems by Harro von Senger.  ISBN 0140169547
The 36 Stratagems for Business: Achieve Your Objectives Through Hidden and Unconventional Strategies and Tactics by Harro von Senger.  ISBN 9781904879466
Greatness in Simplicity:  The 36 Stratagems and Chinese Enterprises, Strategic Thinking by Cungen GE.  ISBN 7802076420

External links:  
Original text of Thirty-Six Stratagems (Simplified Chinese) With comments and explanations to the preface, six chapters, and afterword
English and French translation of the Thirty-Six Stratagems
English introduction to the Stratagems with translation of each accompanied by examples taken from Chinese and Japanese history]
The 36 Stratagems compendium (German)
Binh phap ton tu va 36 ke (Vietnamese)
"An Electronic Art of War in 36 Stratagems" (French/English)
The Thirty-Six Stratagems (Classic Chinese war theories, 800–300 BC) (English)