The portal's certifcate file is specified in the source code tree, in the file sdk/properties/cipres-prod.properties.  For production, it's /tmp/x509_cipres_prod.  

You can force the certificate to be renewed by:

1) log in as portal2prod@qball2.sdsc.edu
2) stop tomcat and the services:
    tomcat_stop
	loadResultsD stop
	checkResultsD stop
3) Remove the certificate file mentioned above
4) restart tomcat and the services:
	tomcat_start
	loadResultsD start
	checkResultsD start