Does the Serpentine belt on a 2006 Chevy Impala need to replaced at say 5 years or any specfic number of miles?

Depends on the kind of climate you live in if the weather is extremely hot or too cold ,i will personally change the belt once a year good luck

Serpentine belts can last a long time, they are tough. Much more important is condition. The V ribs on the working 'face' side should be free of excessive cracks. Likewise, the smooth 'back' of the belt gets polished by wear over time but it too should be free of cracks and excessive fraying.