This is extremely easy. KEY is to play split screen and dont touch the other controller. I was a rank 7 Jet when I did this and had beast weapons. Choose a level 1 trooper as your split screen partner. Choose level 1-1 clear out all the ants. Now just sit back with and down your other controller over and over. With the much stronger weapons I was able to get the remaining 180 revives I needed in less than 15 minutes. You can also down the AI team mate and revive him or if he keeps reviving your split screen partner, down him and leave him down, or just turn bots off in the menu. This is by far the quickest and most efficient way of getting 250 revives.