1) Download the latest version
On my Inkscape extensions page, locate the extensions.zip file (Step 2 on that page) and click on it to download. The file is called extensions.zip and it is a compressed file.
2) Copy Location of Extensions
Launch Inkscape and go to the top level menu “Edit” -> “Preferences”. A window will pop up and you will probably have to drag the bottom right corner to resize it in order to see everything. On the left side, scroll down to “System” and click on it. On the right side, find “User extensions” and copy the text that appears in the white box beside this label (see below).
3) Extract the files from extensions.zip
Open the application and navigate to the downloaded extensions.zip file. Select extensions.zip. With the right mouse button, launch the file explorer menu and select “Open with” -> “Windows Explorer”.
This will list all the files in extensions.zip (see below). At the top right of the window, there is an icon with the label “Extract All”. Click on it.
This will launch a new dialog window called “Extract Compressed (Zipped) Folders. Here, enter the name of the folder that you copied in Step 2 above.
Finally, click on the “Extract” button in the bottom right corner of the dialog window. Close Inkscape if it is currently running. Next time you open Inkscape, the updated extensions will be running.