From experience with Copilot and I'm feeling the same is true for most other GPS software packages: They will release occasional patches to fix bugs...but they are not well publicized. Any substantive changes...including map updates are only issued in a new release of the software. You will (at least) have to pay the upgrade price....which is a fair proportion of the full price normally.
some of the freeware and shareware solutions out there use raw Tiger data from the U.S. Census Bureau this is available in updated free thanks to our tax dollars. I haven't found a package yet that is as robust and functional as the commercial packages, though, so I use multiple programs and muddle through.