Sumeru, please check that you have following
<property name="hibernate.hbm2ddl.auto" value="update" />
in your persistence.xml files - both for business-central-server.war and jbpm-human-task.war. What you experience might be due to having this property set to create or create-drop which will simply recreate tables when new persistence unit is created - there are two used - for runtime engine and one bor history log.
HTH