The copyright year is the year in which the copyrighted work was created. If nothing is modified or created in a year, then it is incorrect to suggest otherwise by adjusting the copyright year.
Three main categories of IP: Copyright. Applies to creative works. Accrues automatically to the creator upon fixing the creation in some durable medium. Generally lasts the lifetime of the creator plus a bit. There is no copyright for a live performance, but there is for a recording of it. Unless you are Disney, there is not much chance of changing or extending copyright. No registration or disclaimer is necessary. Copyright is automatic. Patents. Apply to novel devices, mechanisms, inventions, techniques. Granted by a governmental agency after application and review. Expire after some time. There is some sort of renewal process, but not indefinitely. Trademark. A mark, slogan, sign, image, or similar that is actively used for commercial purpose. Narrowly scoped to the business and the purpose. You cannot run an Apple computer company, but you could start Apple Sinks and Kitchens Co. Mickey mouse is trademarked. Trademarks can be registered or not, with differential protection for the two states. Trademarks must be actively used (even if registered) or they lapse. You could probably start up Sun Computers today. -gb
