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You can go to the below location and find your gadgets copy the folder for each gadget you want to save and after your reinstall put the folder back in the below location where it came from.
C:\Users\Your User Name\AppData
\Local\Microsoft\Windows Sidebar\Gadgets AppData
is a hidden folder use this tutorial to unhide it, Option 1 step 3 File and Folder - Hide or Unhide
The default gadgets are located in.
C:\Program Files\Windows Sidebar\Gadgets
C:\Program Files (x86)\Windows Sidebar\Gadgets