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...
....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.