I tried to find a way to update my dropbox installation but none of the solutions I found on Internet work.
My system is Xubuntu 12.04 and has
dropbox 1.4.0 installed.
.deb file on the Dropbox web site is the same version.
As you have latest version of Dropbox, and a newer version is not released yet, you don't have to do anything right now. After the release of a newer version, just try to manually download the .deb of Dropbox and install it with the Ubuntu Software Center or use: