Hi Sam,
The Calendar Repair Assistant (CRA) is a configurable mailbox assistant that runs within the Microsoft Exchange Mailbox Assistants service on Microsoft Exchange Server 2010 Mailbox servers.
There is a parameter named “CalendarRepairIntervalEndWindow” which specifies the number of days into the future to repair calendars. For example, if this parameter is set to 90, the CRA repairs calendars on the Mailbox server 90 days from the date it was set. The default value is 30 days.
For more information about the CRA, please refer to http://technet.microsoft.com/en-us/library/ee633469.aspx
Thanks,
Allen Zhang