I have to upgrade exchange VIPs configured using iAPP template for exchange 2010, to exchange 2013 iAPP template

Hi, are you saying that you are already running f5.microsoft_exchange_2010_2013_cas.v1.4.0 for Exchange 2010, and just want to reconfigure it for 2013? In that case all you should need to do is select 2013 to the Exchange version question and all the other values (except persistence, which isn't required) should stay the same. Or you could deploy the template again side by side with the old one using different VIP address(es) and then change DNS to point to the new IP when you're ready.