can you replace the macbook pro retina battery?

Take it to an Apple store or an AASP and they will replace the battery.

Ciao.

Yes, you can, but you have to be very careful not to shock yourself or destroy any of the components of the mac, so I'd rather you go to any apple repair centre and get it replaced. BTW the batt is glued to the back, and the batteries are hard to come by, so yeah