Repair, refurbish, or renew. For example, They're busy fixing up their house, or We fixed ourselves up before we ventured outside. [Late 1700s]
fix someone up. Provide or furnish someone with something, as in He can fix you up with a new car, or Can you fix up my friend with a date for the dance? [Colloquial; c. 1930]
Smooth over or settle, as in You'd think they could fix up these small differences. [Late 1800s]