Rebranding can be tricky. Change is scary, and changing it ALL is definitely scarier. Rethinking a brand is necessary tho, because trends change and brands should adapt to them. Sometimes little adjustments will do the job just fine, and some others, well they need work. LOTS of work. But do not be afraid of giving a new look to your company, because ,who knows, maybe the most discrete change is the one you need to revive what once was lost.
To me, one of the best rebranding jobs was done by Design Army. The USPS new look was a great refresh and long overdue! I am excited to send my next package. (Check the whole job here: http://grand-army.com/work/projects/project.php?project=usps_retail )