According to the documentation here https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/iPhoneOTAConfiguration/OTASecurity/OTASecurity.html
"Reconfiguration occurs automatically if the profile expires or if a VPN connection attempt fails."
Having set up my enrolment server and setting a profile to expire at a set date and time, the profile simply expires and does not update automatically, is there anything additional needed to make this happen?