EUREKA!!!

As an Artificer you’ve developed the ability to instantly recall a prepared or unprepared spell in moments of sudden necessity.  You gain a number of charges equal to your Intelligence modifier, whichever is your spellcasting stat.  These charges reset on a long rest and cost the number of charges equal to the spell's level.  So a second level spell will cost two charges.  This is intended for use on half or quarter-casters who often lack for spells.