Redirect back to workflow from the "Session timed out" error page

When we used Workflow Solution 7.0, we added this script to the end of the workflow projects' ErrorPage.aspx:

<script language="javascript">
    var s = document.getElementById("lblErrorMessage").innerHTML;
    if(s.indexOf("session has timed out") > 0) {
        window.location.assign("?timedOut=True"); 
        // This redirects to https://our-domain.com/our-workflow/default.aspx?t...
    }
</script>    

What this does, is following:

If ErrorPage.aspx is loaded and in the <span id="lblErrorMessage"... contains the words "session has timed out", we immediately re-direct the client browser to a new instance of the workflow that timed out.

In our environment users rarely need to be informed that a session does not exist or timed out. They just want to get back to the workflow.

BUT

In Workflow Solution 7.5, the ErrorPage.aspx does not contain the error description label anymore. So we cannot distinct the timeout error from other errors. We don't want to redirect the user back to the workflow if the workflow itself directs to the error page for some reason... for some reason ... for some reason ... for some reason.. right?

So what would be another way to script the ErrorPage.aspx to redirect back to the workflow URL if the reason of the error was "session has timed out".?

Cheers,

Mikael