Umbrella plant problem
 

I have an umbrella plant that's about 8 feet high, at least 15 years old, and which I was watering by filling up the drainage dish (it took about 3 cups a day). The roots were filling up the drainage dish and becoming unsightly. I called a nursery and they said it should be OK to cut the visible roots off. Now the plant doesn't seem to be taking in water unless I do it from the top (it's been at least two weeks) - and I can see tiny pools on the surface sometimes, so that's when I stop. What REALLY worries me, though, is that I'm getting far more yellow leaves than before. I also noticed that the leaves that never get any sun seem to be staying nice and green. So would it help if I gave it less sun? What else should I do?
Thanks.

Lenona.