If you're looking at your business page as yourself, on the left side you'll see your business "likes". If you click on that, you can easily like all those other businesses as yourself.
I'll use myself as an example. Monica Anderson is my regular FB page. My Spinka is my business page. When I am using FB as Monica Anderson, I would click My Spinka on the left side of my home page. This takes me to my business page. From there, I click "likes" located on the left side. Then, I'll see all the businesses I have "liked" as My Spinka, and be able to just go down the line clicking "like" as Monica Anderson.
Sounds long, but it really takes just a minute.