Yes, there is. Simply run the following rendering request through your browser:
http://servername:port//document.qxp?jjname=C:\Documents\test.
With this request, the Job Jacket file (test.) will be saved in the Documents folder on the C drive.
Important Note: Using this procedure to extract the Job Jacket from QPS involves write access directly to the files system where the Job Jacket will be saved. This constitutes a server security risk and should be undertaken with caution.