Arcane Recovery

You can regain some of your magical energy by studying your spellbook. When you finish a Short Rest, you can choose expended spell slots to recover. The spell slots can have a combined level equal to no more than half your Wizard level (round up), and none of the slots can be level 6 or higher. For example, if you're a level 4 Wizard, you can recover up to two levels' worth of spell slots, regaining either one level 2 spell slot or two level 1 spell slots.

Once you use this feature, you can't do so again until you finish a Long Rest.