I want to be able to deadlift 700 pounds! advice?

I've been deadlifting seriously for 2 years now. I started my freshmen year, I was about 130 pounds max dead around 300 when I started ( I did back exercises before this just never deadlifting or any type of deadlifting) I got 375 quickly and reached a platue. I did a lot of research and altered my workout and got to 425 its been about 8 months and I got 480 last week, and 500 on Monday. I want to get to 700. I feel like that's a strong deadlift. I'm 174 pounds and my question is! What kind of workout for I do? I hear two deadlift workouts a week can work? A speed day and a heavy day. Right now I go in the gym put 10 pounds over what I did last week (next week it will be 510, I keep settin a new max every week) and pull it once then do 3 sets on sumo's and three sets of snatch witgh 405. what else? What can be changed?