Thoughts on a sensory/autistic diet

Developmental Therapy today was not good enough. Jen arrived and Nikko did not want to sit in the corner by the couch and work. In fact, I spent almost all of 45 minutes restraining Nikko, keeping him from leaving our corner, trying to sit him down or in my lap, or corralling him from hopping over the couch to escape. I had a real workout, let's just say. There were a few instances where he looked at Jen's stuff and complied: he started with putting a powdered hand print on black paper, he assembled two puzzles by HOH, he sorted a few colored shapes into containers, and the best attention-getter wasn't the bubbles this time but threading colored vehicle-shaped beads onto a black shoelace. He had to manipulate the bead so the lace would poke through, definitely fine motor skills at work. But after each activity he would glance around and become a slippery fish wanting to swim outta there. Audrey was nearby and because it was close to her naptime, she was able to snooze a little bit before Nikko made enough of a ruckus to wake her up again. I wasn't happy with the results of today because even Jen had to work harder than usual with Nikko. She remarked that he acts like he forgot how we do things, and I said that probably not seeing her for two weeks plus not having speech therapy yesterday made him not want to be pinned down to the corner. I was kind of embarrassed because it looked like he hadn't been challenged in quite a while, therefore he was rebelling. Maybe that's not really the case; I try to challenge him by asking for More every day. But this also leads me to wonder what I can be doing with him so that when therapy time rolls around he makes progress instead of steps backwards. I am not really referring to the Levy book again on this, but I think I'm venturing into that realm of doing a daily autism/sensory diet. I've thought about it before, but I'm not a therapist. I don't know exactly what I can be doing with him every day. Is it as simple as saying that I should work on at least one puzzle with him every day, or that we should do a matching/sorting activity every day, or something akin to that? If so, should it be one activity to stimulate gross motor, one for fine motor and one for speech, each and every day? And then, what activities under each header could I pick from? I know that the therapists will tell me it's as simple as letting him go outside to splash in puddles or dig holes in the ground with sticks, but that's only because I've seen him do this with the therapists. Otherwise, I wouldn't know that even the simplest activities could qualify as "daily therapy". I don't think like a therapist so I don't readily identify these things. Is this something I should just learn to do? And how am I supposed to do this?