Most people are so relieved to finally get their bio written, they tend to post it and forget it. Does that sound like you?
How often should you update your bio? The answer varies with the person, of course, but a general rule is whenever something noteworthy happens, or at least once a year. Chances are good that something has changed in that time, and your bio should reflect that.
Did you get a promotion? A new certification? Join a board or other professional organization? Has something happened to your company (not necessarily you)? All of these events merit an update to your personal or professional bio. The good news is that you are not starting all over! You have already written a great bio, keeping it updated is a piece of cake!
One client came to me and asked for my help in updating his bio. I asked him how long it had been since he wrote it to begin with. "A few years," he said. "It says my kids are 8 and 10, and they're in college now."
On a related note, many people don't update their bios because they don't have access to their website, whether it's their own or their company's. That's a whole different hurdle that we can discuss at a later date. For now, when was the last time your bio was updated? If more than a year, go forth and update!