Sometimes stepping away from one exercise can help. Squats also build your back, hips and core a whole lot, that could have helped too.Quad strength is probably the most important thing to have for a strong deadlift. I **** you not, I was stuck at a plateau for a whole year, if not more on deadlifts, I decided Id focus on squats, because it was lacking behind by a good bit (Hence, weak quads.), so I did the full Smolov program. I didn't deadlift for 4 months because it was a squat only program (And didn't bench, yeah, that was dumb, I just now got back to my previous 1RM from before Smolov, a year ago.) and I decided I'd test my 1RM's to build myself a personalized program... I broke the deadlift plateau. Didn't just break it, actually. I obliterated it by 80 pounds.
Louis Simmons swears by sled work because he was plateauing his squats around 650lbs, he couldn't break his 1RM. He decided to not squat and do 6 weeks of sled work, he squashed his BS 1RM after those 6 weeks.