Then you modified the wrong conf/log4j.xml. This file is read at whatever RefreshPeriod is specified in the config/jboss-service.xml. The default is 60 seconds.
I have not configured the wrong file. After I have added the refresh-attribute and set it to 30 s, the server recognized the changes and it works fine. Must I set the refresh-attribute in JBoss-Versions < 3.2.6?