Why would a business want to re brand?

It is an opportunity to get lots of attention for their company and products. A new brand may be more appropriate as times change. It may reduce confusion with a similar brand. It can happen when the company changes in some way, such as taking over another company and wanting to maintain some element of their brand. It may done as a fresh start, after a company has been having problems. Companies may be changing the type of business they do or adding new elements to what they do, and so they want their brand to reflect that. For these and other reasons, companies rebrand.