frequently, often, again & again
屢 centers on repetition: something happening frequently, often, or again and again.
屢 is a phono-semantic compound: 尸 (body) suggests a bodily action, and 婁 (a character associated with tying or frequent) contributes the sound and the idea of repetition. The exact historical development is uncertain.
Under the 尸 roof, the complex 婁 looks like a repeated pattern of boxes and lines, like something happening over and over.
For ル, imagine a looping roller coaster that goes again and again: loop -> ル, and the ride repeats frequently.