He needed her to show herself. He needed her to think he was still in her thrall.
After spending a few months on a rehab/psych ward, Archie checks out of the hospital to investigate what appear to be new Beauty Killer slayings, but turn out to be copycats committed by a Beauty Killer Fan Club.
Things Archie does immediately after leaving rehab include: Getting a gun and phone from druglord Jack Reynolds, scouring a crime scene for pills to steal, and attending a secret meeting of the Beauty Killer Fan Club.
At the fan club meeting, Susan gets a needle stabbed through her cheek, and Archie gets tased a bunch and then kidnapped and suspended from hooks.
After getting rescued from that predicament, Archie goes back to Henry’s house, where he’s staying for the moment, to get a shower and some rest. When he gets out of the shower, who else would be waiting for him but Gretchen? He tries to kill her but gets cold feet, so she tases him and leaves him with the clues to track her down. He finds her in the process of killing the copycat. Given the option of saving the killer or catching Gretchen, Archie lets the killer die and manages to arrest her and put her back in jail.