Update Dropbox for Ubuntu 11.04

• Download Dropbox v1.1.31 (Linux x86, Linux x86_64)
• Delete ".dropbox-dist" from the home directory
• Extract the downloaded Dropbox to the home directory (the extracted folder will be ".dropbox-dist")
• Stop the currently running Dropbox if the old version Dropbox exists by running

killall dropbox

or

dropbox stop

• Start Dropbox by running

dropbox start

Ref:
http://forums.dropbox.com/topic.php?id=37361