While upgrading CA Live API Creator from version 3.2 to 4.0:--
1) does " war deployed on JBoss " needs to be undeployed first " and cache needs to be cleaned in present setup?
2) does new war 4.0 is to be deployed over existing 3.2 war in JBoss?
The upgrade to the newer version is simply a WAR file replacement of the existing WAR file.
Depending on your JBoss configurations, there are occassional exceptions (e.g. if your JBoss setting for autoDeploy is not set to true). Consult the JBoss docs here.