Edit the file "C:\Program Files\D-Lab\settings.xml" (right-click > Edit).
Within the Settings-Section of the file (between <Settings> and </Settings>) add a line
STORAGEFOLDER can be any valid folder or harddrive.
Example: <Storage DataRootPath="D:\Data"/>".
The data will then be saved and read to / from this new folder. If the folder does not already exist, it will be created during the next start of D-Lab.