I've seen many of my students use the copy/paste functions to copy their whole A B A melodies and paste them in a new staff. After that, they chip away at the copied melodies, selecting portions to double or harmonize the main melody and other sections to erase or thin out.
My favorite application of the simple repeat (and the part of "Developing a Melody" where I spend the most time in class and with individuals) is the small sequence idea. My students seem to get the idea of repeating a 4-measure melody and then sequencing the whole thing, but picking a small part to sequence has been harder for them. I've seen very few examples that happened without my influence.