I've dug around a little, and found some sites with information, including the CRS that outlines making a will in the state. If you've got a will already, I would write your new will, bring your witnesses and the new will to a notary, and add some sort of notation on the new will that states that it takes precedence.

Here are some sites for your perusal:
http://resources.lawinfo.com/estate-...ills/colorado/
http://www.nolo.com/legal-encycloped...ill-32143.html
http://www.cobar.org/index.cfm/ID/20909