The word "bangs up" refers to causing damage or harm to someone or something. The antonyms of this phrase could be "fixes up," "repairs," "restores," or "mends." When something is fixed up, it means that the damage has been taken care of, and the item is as good as new. Repairing something means to restore it to its original condition, and restoring entails bringing something back to its former state. Mending is a term used for fixing small damages that don't require extensive repairs. In summarizing, the antonyms of "bangs up" are all about fixing, repairing, and restoring broken or damaged items, not creating more harm.