There is a shortcut. The problem is that there is an absolute path to the SOPC system (.ptf) file in the system library. It's located in the "system.stf" file inside the system library folder. When you copy the projects to a new folder, just edit the "system.stf" file to point to the correct path. Or better yet, you can replace the absolute path with a relative path (i.e. "..\<quartus_project_dir>\<sopc_system>.ptf"). Where is <quartus_project_dir> is the directory where your .ptf file is located and <sopc_system>.ptf is the name of your ptf file. Hope this helps.
Jake
