There's no official replacement for spells. Sorry.
Actually, there's only a couple ways to get rid of 2/3 casting. The Investigator has a couple of archetypes that give up its alchemy. No other class with 2/3 casting or higher has a Paizo archetype that gets rid of spells.
Also, Ultimate Intrigue is set to have an Alchemist that gives up extracts for shape shifting.