usually if they declare war on me i continou untill they are dead

I've never seen the AI come back from a losing position either.

I have seen an AI recover. The Drenjin got beat back to one system, witht he rest of the galaxy occupied. Then I got jumped by all the other races (which I had been supporting in thier wars against he Drenj. ). That ticked me off, since I had basicaly been spoon feeding them all. Well, under thier combined might, they (about six or seven races) beat me back to three planets, so I decided to take everyone down with me. I gave all my tech to the Drenjin, and what little money I had I gave tot hem, or purchased some minor conflicts between those attacking me. Suddenly, with everyone focusing on finishing me off, the Drenj. came unglued on everyone, and with ships sporting my superior tech, they anniliated the galaxy. One by one, EVERY civ. who betrayed me surrendered to me in hopes I could save them, but by the time that happened I was economically broken, and the galaxy soon fell.

It was the most I've ever enjoyed losing. I was laughing like a maniac the whole time, revenge is awesome.

More on topic, when I have someone beat, I'll only stop if I run low on troops, then I'll declare peace for a few months while I restock, then finish them off before they surrender to someone I like.

I've never seen them recover from a military defeat, though I once had the entire galaxy turn around and sack all my starbases half way through the waiting period at the end of an influence victory.

Once, in a game I'm still playing, the Drengin were badly beaten by the Drath. I'm sure that it had something to do with a Precursor ship that the Drath uncovered. Anyway, although I kept out of the actual conflict, I cranked out a pile of ships to keep the Drengin fighting. I even built them a few starbases. Basically I saved them from total annihilation

Then, when I had my economy in order and a big pile of ships for myself, I joined in the war and ground the Drath beneath my heel while they were still trying to crank out enough ships to counter the newly-armed Drengin. After taking a few of their planets with ease and wiping out the defences of the rest with ease, they quickly surrendered.

Now I just have to worry about the Drengin accidentally vaporising stuff with their plasma weaponry

I always finish a game if i get that far because i do metaverse.

Usually I can just press end turn like 20 times and win a cultural victory. Often I have it set up so i can do that in the end.

Since my last post in this thread, I have seen an AI come back from the brink.

The Altarians declared war on the Korx, who started in a bad spot and only had 4 or 5 planets colonized. The Altarians had maybe 2 dozen planets and a huge military. Somehow, amazingly, the Korx absolutely whomped the Altarians and took their whole empire, minus the last 2 planets which they surrendered to the Iconians. I don't know how the hell they did it.