This appears to be a bug. Your onPageShowing() method should be called if the PageState values are changed.
I have created a bug for this on the Errai JIRA. You can track the progress at [ERRAI-793] Page not reloaded correctly if user navigates to same page but with different page state values. - JBoss Iss….
In the meantime, can one use @PageShown and expect it to work.