The short answer is Yes....add more as needed. ~~~ Cooking on a slow simmer with a lid on hopefully the evaporation will be minimal. How much other "stuff" (vegetables) you add will have an effect too...Personal preference comes into play as well...How "soupy" do you like your beef stew...I don't want to make soup, but I don't want it to be dry either...somewhere in between....HTH
Enjoy!