Well... first, there were two major fights at Repleetah. The numbers you have (2.7 million human troops, 1.2 million human civilians and 7 million Kilrathi) come from the first -- a traditional fight that lasted from 2646.080 until a Kilrathi withdraw on 2651.290.
Numbers for the fighting that killed *everyone* (2654.287-late 2664) aren't known.
A lot of those losses are because we were on the defensive -- remember the statement in End Run that it'd take ten imperial legions to dig out a single fortified human division from Vukar Tag... the losses of the side that has to make an amphibious landing are going to be far, far higher than those on the defensive.