Plateaus with vengeance

I have been on and off the health wagon a LOT in the last 2 years since I started, but I finally decided to go gun-ho and really make a lifestyle out of it. I have seriously cut back to almost no drinking at all (one every once in a while, no beer), more strength training, HIIT 3 times a week, active rest (yoga or pilates for 30+ minutes), and making my days off useful and meal prepping instead of going out.

BUT. I always hit that plateau. My workout is almost completely different every time I work out; I mean, FB has so many videos, why would you stick to just 5 videos over and over again?

I don't know if I need to up my weights because I still struggle with the last 2 reps (like I should) with any strength training.

Is it my HIIT routine? Do I need to crank that up? Because I definitely still sweat my butt off with those routines.