Leveling multiple acres?

Hey guys, I bought a house last year on 4 acres and the previous owners kept about 2 acres as a Prarie with grasses about 3-5ft tall. We've cut down the field last year and have maintained cutting it every week to incorporate it as our yard as well. My issue is, it's extremely bumpy. Back breaking bumpy.

I never bag my clippings, I always allow them to break down back into the grass, will that eventually over time help build up low spots? Or do you guys have any ideas on leveling a large field? I appreciate it!