I have a bow that has Power IV, Flame II, Punch II, and Infinity I, and also it's renamed. According to the wiki, that has a base value of 38. Since the max level is 39, that would mean practically anything I want to do is above the max. Is there any way to repair it?
As fredley stated, you cannot repair it in game. But since you asked for ANY way to repair it, you could use NBTExplorer to set the damage of your bow to 0.
Simple open the
level.dat file inside the folder of your world with NBTExplorer and klick
Search->Find. Tick the two checkboxes and search for name:"id" and value:"261".
This will quickly show your bow, now you just have double-click "Damage" and enter 0.
That's it, your bow is saved ;) ( btw: that's an awesome bow! )