If you have completed the design of your web site, in no way does it mean you can relax and practically "forget" about your site. If you wish to have a successful web site, you should be ready and willing to work hard. In order to succeed, a necessary action by the site owner is to regularly update his/her web site. By having fresh content and regular updates, it should surely help you towards building and maintaining a successful web site. The benefits from regularly updating your web site will not only be shown from users desiring to visit your web site more often, but the search engines will love this too. A web site that was designed in 1999 and has not been touched since will most likely not do as well as a web site that was setup in 1999 and has been updated multiple times per month since day one.
Never forget about the importance of regular updates to your web site. Never be satisfied with the web site you have live, you can always do better.