You can do upgrade manually. Go to the /usr/pluto/bin and run one by one two scripts:
The first one will download all updated packages and the second one will apply changes to the pluto installation.
Note: you should wain until DownloadUpdates.sh finish. Also, you can ignore some warinigs which may be generated by this script (you can see the log /var/log/pluto/DownloadUpdates.log)