Hi R Guru,
Crystal Server 2016 i.e. Version 4.2 was scheduled to released in late March 2016 probably. Currently 4.2 is in Ramp up and I believe it will be available for customers soon.
For reference you can check : Waiting for SAP BusinessObjects Business Intelligence 4.2
BI4.2 GA is planned for Q1 2016.
It will be available as Full Build and you can also update Crystal Server 2013 to 2016 as it is 4.x architecture.
Regards,
Mahak