The original configuration properties file (see e403 Configuring Logger Default Values with a Properties File) can be reread using LogManager.readConfiguration(). This method fires a PropertyChangeEvent. 
    // Register for the event
    LogManager.getLogManager().addPropertyChangeListener(
        new PropertyChangeListener() {
            // This method is called when configuration file is reread
            public void propertyChange(PropertyChangeEvent evt) {
                String propName = evt.getPropertyName();
                Object oldValue = evt.getOldValue();
                Object newValue = evt.getOldValue();
                // All values are null
            }
        });