Cisco AAA/Identity/Nac :: AD Password Change In ISE 1.1

We're running ISE 1.1 for guest services.  We use Active Directory for Sponsor Portal login, as well as for administration of the ISE itself.  Our corporate policy requires a password change for service accounts, and the service account password we use for ISE to connect into AD expires in a few days.  So I changed the password on the account, but how do I tell this to ISE?  I don't see anything in the documentation, only some references to only use non-expiring accounts to connect to AD.  This made me laugh.  If our corporate policy was that lax, we'd never have purchased ISE.
 
1) Is there a way to communicate this to ISE?  Or is leave and then join the only way?  Will that even work?

2) I see that after the password change, ISE continues to work fine.  Does it only synch with AD periodically?  On reboot, or every X hours?  Right now things are working, but I'm afraid as soon as I turn my back it will stop.