Slackware uses a package called swared for package management. The last release of it was in 2004 but it still does work with slackware 11.0 and likely will work into the future. If you use that package manager edit its configuration file and specify 11 for the version or current for the version you want to maintain on your system before running the package for the first time and you should be good to go. Other package managers for slackware did exist but they've fallen by the wayside due to lack of maintenance. Some of them have hard limits on what version you can upgrade to built into them believe it or not!
