You really never want to take on an account assuming it won't work out. Find out exactly what is required per mowing, and bid it just like any other job you have. As others have mentioned, the size of the cemetery portion and the placement of the stones will have a lot to do with the time required. I've only mowed one cemetery, helping a friend of mine before I started my own business, but it was an old one (has one Revolutionary War soldier buried there), and the stones are scattered helter skelter. Figure it will take you twice as long to mow as it would to do open ground of the same area, then figure up to a minute for each stone for trimming. Good luck.
Dependable Mowing Service