My kids have little waists (so skinny they could still wear baby clothes if it weren't for the length!) so their jeans have the potential to last a long time.
When my kids get holes in their jeans, I've mended and patched them, but I prefer to chop off the legs and turn them into (FREE) shorts or skirts.
My daughter had a ton of jean shorts (some with cute ribbons or lace sewn into the hemline) so I took the last two pair she outgrew and turned them into skirts.
It's really simple to do.
This is her favorite skirt. It's made from the legs of her other jeans:
This one is made from jeans and the bottom of a top I no longer liked.