The repair, if Apple would even do it, would likely be replacing the logic board, and probably the top case, which includes the keyboard. I will guess somewhere between $900 and $1,300.
It will depend on how much liquid, and where it went inside. If it was only a few drops, and some sticky keys, and not so much to get inside, with all the sugar and acids that are part of most juices that quickly will disable your laptop, then a shop may just be able to clean the keyboard (although that's really iffy, too, on the newer keyboards.)