Chasing a PR (Personal Record) is an obvious way to note proress, but how about the little things?
For example, with your accessory exercises, are you improving there? Maybe it's 1 rep or 5 lbs. What about sleep, are you setting your alarm 5 min later or better yet, going to bed 5 min earlier? Maybe you are tracking your water intake, how about 4 more oz?
Celebrate and take note on big steps in progress but don't overlook the small stuff, they produce big results.