Need more calories, or more snacks?

coopahson

I am 52 years old, 6'3 and weigh 226 lbs, down from 266 about 6 months ago. I have been eating about 1800 cals a day and, according to my Polar device, burning 800-1000 cals during my 6 times a week workout. This net gain of 800 cals resulted in great weight loss for 5 months, but now my metabolism has slowed, my weight loss has stalled.
I have done some searching on the web, but a little confused. I guess I need to jump start my metabolism so do I maintain my caloric intake but eat more snacks, or do I add about 600 calories a day to my diet and continue exercising, making my net gain about 1700 cals?
My diet is healthy, lots of fruit and veg. I do not eat meat and would have to force myself to eat more. Ironic that six months ago I was never satisfied and could eat all day, now I need to remind myself to eat something.
Also, does drinking a lot of water increase metabolism? One thing I don't do is take in enough water.

Cheers