Hello ymf331 - I've been using Slackware for a few years now and, as for me, I just upgrade to the next Slackware version once a year. So, I have a different set up than you do. In my experience, though, programs almost never depend on the kernel version you're running. When I do upgrade the kernel however, I usually have to recompile my video drivers and any other software that comes with their own kernel modules (like VirtualBox).
For keeping system programs up to date there is, as I'm sure you know, slackpkg (for you - syncing with slackware-current, for me - 14.1). For keeping your SlackBuilds.org packages updated, there is sbopkg. Also, there's an extension to slackpkg called slackpkg+ for staying updated with 3rd party repositories (like alienbob's): http://alien.slackbook.org/blog/intr...-repositories/
This probably wasn't too helpful for you, but it's just my two cents.