Here are some things you might be thinking as you are considering a re-design:

It’s been 2 years since our last redesign.
Our current stuff just looks old.
Our competitor has a nicer looking website. 
A redesign would bring new traffic to the site.

Those are good observations to have, but they are merely symptomatic. Too often, look and feel, color scheme, theme, and layouts are presented as solutions to problems before regard is given to other less-aesthetic issues that may very well be the root of the problem. Don't treat the symptom instead of the root cause.

Don't Redesign, Re-Align

Cameron Moll talks about this in an article he wrote on the subject. He so eloquently put words to a design philosophy we hold at ClikFocus. We only "re-design" what is necessary to strengthen your online presence. True, at times, a complete overhaul is necessary. But more often than not, a simple spring cleaning is what you need to bring your company the momentum you are looking for.

Too often redesign exists for the sake of redesigning. It has no authentic meaning or strategy. A realignment, on the other hand, evaluates the long term vision and goals and asks if the design can be adjusted to add to that vision.

When thinking about doing a realignment, be sure you are addressing the root problems - not just symptoms such as, "our competetor's website looks better". Here are some healthy things to be thinking:

We have added new types of content that is not being presented as well as it can.
Market trends have shifted.
Our user's needs have changed.
Does our online presence enhanve or devalue our brand equity and over perception of our brand?
Our website does not convey the strength of our product offering.

Raison D’être

Freanch for "reason for existing", you want to evaluate "why" rather than "what" needs to be redesigned.

Ensure your “raison d’être” exists. What are the reasons/objectives/purpose for realigning?

Determine what level of realignment is required. Will minimal changes suffice, or is a total revamp necessary? A solid raison d’être will aid in answering this question.

Think of the cost to the user. What will the impact be to users of the site? Will they be forced, enticed, or encouraged to mentally “switch” to the realigned design and any changes to the user interface, navigation, color scheme, etc.? How painful or painless will the switch be? Would an incremental redesign be better?