A cool and easy way to repair knee holes in jeans is to sew on the back pockets of a pair of older jeans. It’s hard to get my daughter to part with her favorite pair of jeans. Sometimes when summer comes we make them into shorts but if not, here is a solution.
You will need a pair of jeans that you can salvage the back pockets from. I like the ones from smaller jeans. You might have some that your child has worn out/ out grown. I used a seam ripper to remove the pockets then I sewing them over the holes of the jeans that we want to keep. I left the pockets open on the tops but you can sew all the way around if you like. When salvaging old pockets, you may want to cut the pockets off instead so that you have two layers that you sew on.
They are approved by fashion conscious people (like my daughter).