I routinely make calls to the AzAuthorizationStoreClass.UpdateCache method.  For example:

AzManStore = new AzAuthorizationStoreClass();
AzManStore.Initialize(0, StoreConnection, null);
AzManStore.UpdateCache(null);  // this causes the store to refresh and have access to the latest changes
AzApplication = AzManStore.OpenApplication(ApplicationName, null);