Try the following
-Backup the database
-Rename the database to "lansweeperdb"
-Upgrade the database using the upgradescript found in the forum (upgrade sql.sql)
-run the installer on the service server, select new installation and select only the service to install, point to the existing database.
-run the installer on the web server, select new installation and select only the website to install, point to the existing database.
-Run the installer again, it will detect the outdated database and will upgrade it.