You can manually download the latest patch - I had to work out what the update was doing so I could to do it manually as my main machine is behind an authenticating proxy and the auto update doesn't work with authenticating proxies.
I would share how it's done, but if Gernot hasn't published it so I don't want to get in trouble if there's a reason it hasn't been published.
The number one reason I think would be that installing it manually doesn't do the nice step that the automated install does of backing up your old version for you. If you manual take a copy of your GLBasic directory beforehand and overwrite the files yourself then you can easily back out the update by copying back your backup copy.
The only other reason I can see it would be kept quiet would be if applying the patch to a demo version turned a demo version into the full version - obviously then providing the location of the patch wouldn't be a good thing. I would hope it doesn't work that way.
So, assuming updating the demo with the latest patch doesn't turn it into a registered version, then if a mod will approve me posting it, I'll post the address where you find the most recent patch to apply manually.