Edit the file "C:\Program Files\D-Lab\settings.xml" (right-click > Edit e.g. with Notepad++). 

Change STORAGEFOLDER (default: C:\data) in line 4...

        <Storage DataRootPath="STORAGEFOLDER"/>"

....to any valid folder or hard drive.

Example: <Storage DataRootPath="D:\data"/>".

D-Lab stores and reads data in/from this new folder. If the folder does not already exist, it is created during the next start of D-Lab.