Any item that restores magic points and/or spell uses.
Some support Mana Potion for the name. If that gets a few more replies supporting it, that becomes the trope name.
Any item that restores an amount of Mana a character has, or restores spell uses in the case of Vancian Magic. The amount can vary, from just a fraction of a Mana Meter/one use of a low level spell, to restoring all the magic points/restoring all uses of even high level spells. If there is a range, the lower level restoring items will cost less and be more plentiful in Treasure Chests and Random Item Dropping, although those tend to be much rarer than healing items. Note that this doesn't count when spells simply need material components to cast. Then casting more spells simply means getting more of those items. Nor does it count if mana has to be built up. Then it's not restoring, but acquiring. Also note that Trauma Inns, Healing Springs, and Healing Checkpoints often restore magic in full as well as health. A Sub-Trope of Standard RPG Items. A Sister Trope to Auto Recharging Magic, Healing Potion (restores the Life Meter), Panacea (heals disease and status).