If you’re using subversion, just right click on the Beethoven directory, and select
TortoiseSVN->Update. This will download the latest version and overwrite any existing files. You can always revert to an older version if you decide to.
Feel free to check the svn log if you’re uncertain about what changes have been made.
If you’re not using subversion, you can download a zip file and decompress it to your desktop. Since it’s acceptable to have as many Beethoven folders as you’d like, renaming each folder with a version number and keeping multiple copies of Beethoven on your computer works. Subversion essentially handles this for you automatically, but if you prefer to have more control you can follow this manual method.