Death lurks in the background of "Lord Randall" until it jumps out and yells "Surprise!" at the end. And once that big reveal happens, we can't help but look back and see death everywhere. Lord Randall may not slink off and die until the last line of the poem, but it is foreshadowed pretty heavily through his emphatic repetition of the refrain. In some ways, this poem requires multiple readings; the first time, you go through it and feel surprised and saddened by the twist at the end, but the second (and third, and fourth…) times, knowing that death is the ultimate ending here just makes the whole thing a lot sadder all the way through.
The incremental repetition in "Lord Randall" evokes a sense of gradual resignation towards the Randall's inevitable death.
Lord Randall's apparent acceptance of his fate implies that he cannot bear to live without his untrustworthy "true love," suggesting that he believes a life without love is not worth living.