These docs are for an old release.
Info on upgrading to v4
refetchEventSources
Refetches one or more specific event sources.
.fullCalendar( ‘refetchEventSources’, sources )
The sources parameter can be a single identifier item, or an array of identifier items. An identifier item can be either an event source’s id/Array/URL/Function or the full Event Source Object.
Will result in a single re-rendering of events when all event sources are refetched.