There is no automatic backup and restore feature included with iManager. iManager is composed of two parts: the local files on the server and the Role-Based Services objects in eDirectory.
To make a full backup of iManager, make sure you have a valid backup of the RBS collection and all subordinate objects in the tree, either through replica redundancy or with an eDirectory backup solution.
All local iManager files on the file system are stored in the Tomcat directory. As long as you have a backup of the Tomcat directory, all iManager content is preserved. If the Tomcat directory is somehow compromised on the server, shutting down Tomcat and recopying the directory allows you to recover iManager. If you are not using RBS, backing up the Tomcat directory is all that is needed.