you could keep your feet together, or more spread apart on your leg press, hands closer or wider for bench, etc.. and alternate between your normal bench, squat and the modified version...
start incorporating machines into your lifts, but DON'T stop using barbells entirely
try finding ways to tweak your lifting, but don't DRASTICALLY change it if it was working for you in the first place
one big thing that i would change is the time it takes to do one rep.. i would drop the amount of weight you're doing and do "4/0/2" reps... meaning take 4 seconds to do the negative, 0 pause, 2 to actually lift the weight... and you could switch it up to whatever you choose.. put in a 1 second pause etc..
the most important part to getting out of a plateau is to keep your muscles guessing