Reprepare Spell

You’ve discovered how to reuse some of your spell slots over
and over. You can spend 10 minutes to prepare a spell that
you already cast today, regaining access to that spell slot. The
spell must be of 4th level or lower and one that does not have
a duration. You can reprepare a spell in this way even if you’ve
already reprepared that spell previously in the same day.

If you have the spell substitution arcane thesis, you can
instead prepare a different spell in an expended slot, as long as
the new spell doesn’t have a duration. Once you’ve reprepared
a spell in that slot even once, you can use your arcane thesis
to substitute only spells without durations into that spell slot.