You’ve been butting up against the same max for months, unable to break the plateau.
Load the bar with 25% more than your max weight. Have a spotter help you unrack it, and hold the bar over your chest with a slight bend in your elbows for five seconds. Rerack the bar, then rest one minute. Reduce the weight to 2.5%–5% more than your max. You’re ready to set a new record.
Called post-activation potentiation (PAP), holding a heavy weight temporarily increases the sensitivity of your muscles to calcium. The effect is a sudden increase in strength. So give it a try, and see how much more weight you're able to lift.