Does anyone ever play with research victory?
I do sometimes, especially if I'm playing a game with more than two teams. Really nice to have that I'm done now button to win once you have a ton of resources.
Anyways, to the OP, there isn't a mod just for the AI, but as mentioned you can probably fix the retreating issue by making your own little mod. Find your mod folder, make a new folder called "My Mod", and make a folder in there called "GameInfo". Then go to your game directory in the steamapp folder (for Rebellion), find the folder called "GameInfo" there, then copy a file called "Gameplay.constants". Paste that file into the GameInfo folder of the mod folder you made. Then, open the copied Gameplay.constants file in notepad, then search for the RetreatThreshold line previously mentioned. Play with the numbers and see if it helps (I don't remember if making it larger or smaller makes the AI fight longer, but you should be able to get them to fight to the death).