I once described this novel, to a student, as being not about happy or sad endings, but about what was left of the characters when it was over. "No Country For Old Men" definitely has a tone of disillusionment and fatalism that give rise to many examples of loss and survival in a semi-cyclical relationship.
Spiritual Loss/Loss of Faith: Bell says at one point,
I always thought when I got older that God would sort of come into my life in some way. He didnt.
Bell hasn't exactly lost anything (since he's implying God wasn't in his life, so he had nothing to lose) but this is more of a sense of disappointment; Bell was probably looking forward to peace and guidance that never came.
Bell's decision to retire can also be seen as a loss of faith in both himself, and the role of law enforcement.
These old people I talk to, if you could of told em that there would be people on the streets of our Texas towns with green hair and bones in their noses speakin a language they couldnt even understand, well, they just flat out wouldnt of believed you. But what if you'd of told em it was their own grandchildren?
This quote comes amid a passage speaking of disillusionment and a change in times. The point is that America is becoming unrecognizable to Bell and those like him.
Financial Loss: Loss of money is the reason for Chigurh's entrance into the story, and in the final paragraph, Bell mentions dreaming of having lost money that his father gave him. Money is most likely a MacGuffin which represents responsibility, success, dreams, etc.
Loss of Life: Death appears frequently in the story, and can be thought of as an ultimate loss. Death is one of, if not the primary, consideration for Bell when he decides not to pursue Chigurh when it becomes clear that this will be likely to end with his own death and Chigurh's escape.
Loss of Control Over One's Fate: Chigurh is sometimes depicted as a ghost, and the death that he brings as a force of nature. His conversation with Carla Jean emphasizes his own inability, as well as Carla Jean's, to alter the course of fate; everything is proceeding as it "must".
Everthing I ever thought has turned out different, she said. There aint the least part of my life
I could of guessed. Not this, not none of it.
Survival of Evil: The fact that Chigurh "wins" in the end is significant in that it implies that evil will always endure, and sometimes is too much for anyone to resist.
Survival of Injury: Chigurh and Moss both seek medical attention after trading shots, with attention being paid in Chigurh's case to antibiotics, suggesting that he has been educated at least well enough to understand bacterial infection and to consider long-term prevention and care rather than just stopping the bleeding.
Survival of Guilt: Bell's guilt over abandoning his squad in World War 2 stays with him for the rest of his life, and motivates him to do some sort of good as a means of repayment.
Survival as a Choice: Bell's decision to retire comes with his recognition that he can no longer make a difference, that he values his life too much, and that continuing to do his job would result only in his death.
Survival of the Human Spirit: The title of the book comes from the poem "Sailing to Byzantium", which states:
An aged man is but a paltry thing,
A tattered coat upon a stick
Much as Bell wants to do the right thing, he comes to realize that he has aged out of this world, and though his spirit endures, he cannot play an active part.