If you’re hoping to become a resource to prospective clients, then it’s important to update your website’s content. Dedicate a place on your site to educate your prospects so they can begin to see you as that resource.
Updating content regularly will also help you with the search engines. Google specifically focuses on dynamic content (content that is changing regularly). It improves your ranking or position in the search engine.
Lastly, if you’re committed to updating your website through a blog or some type of news format it can actually be a good exercise for you to keep your website current with the changes in your business.