I followed precisely the directiohs in the support document "
HT5358: Lion Server: Renewing Profile Manager's code signing certificate". When I enter into Terminal.app the command line required to renew the certificate, I get back the reply: "sudo: /usr/sbin/certadmin: command not found"
I found the solution. The certadmin has been moved by mountain lion. Here is the entry that needs to be placed in terminal.app:
sudo /Applications/Server.app/Contents/ServerRoot/usr/sbin/certadmin --recreate-CA-signed-certificate "myserver.mydomain.com Code Signing Certificate" "IntermediateCA_MYSERVER.MYDOMAIN.COM_1" 192173c1c