After the first time checkout is done, updating your sources is simply done by typing (in the Wireshark source dir):

$ svn update

This will only take a few seconds, even on a slow internet connection. It will replace old file versions by new ones. If you and someone else have changed the same file since the last update, Subversion will try to merge the changes into your private file (this works remarkably well).

Independent of the way you retrieve the zip file of the Wireshark sources (as described in Section 3.3, “Obtain the Wireshark sources” ), the way to bring the changes from the official sources into your personal source tree is identical.

First of all, you will download the new zip file of the official sources the way you did it the first time.

If you haven't changed anything in the sources, you could simply throw away your old sources and reinstall everything just like the first time. But be sure, that you really haven't changed anything. It might be a good idea to simply rename the "old" dir to have it around, just in case you remember later that you really did change something before.

Well, if you did change something in your source tree, you have to merge the official changes since the last update into your source tree. You will install the content of the zip file into a new directory and use a good merge tool (e.g. https://winmerge.sourceforge.net/ for Win32) to bring your personal source tree in sync with the official sources again.