I am glad that you have managed to upgrade your projects.
On the following article you could find information about our installers and how do they upgrade each other: Major and Minor releases.
Also have in mind that if you use the Telerik Control Panel, by default it always removes the older versions of the product when you are installing the latest one (and this is the reason why the projects are broken).
However this is an option which could be changed in Telerik Control Panel. For more information on how to do that you could refer to the Help section of the Control panel (just start Telerik Control Panel and you will see an icon with a question mark on the top right corner).