With Alexa remembering everything that happens on each loop, while Melvin and Lexxx don't, this lets her probe them for weaknesses without them being able to adapt. Imagine a different attack on Lexxx's security each day, like when she caused her to use the strap-on on him. Imagine that after an attack like that, her security would beef up and prevent further attacks, but that would all reset when the loop does, with only Alexa remembering that weakness. And then imagine if she collects all six weaknesses, then sets a trap so when Lexxx connects to our guy's PC after the prom she gets hacked and controlled by Alexa.