M.H.
Hi A.,
First of all, don't give her Karo syrup. It usually works for constipation but it is just like honey as it sometimes has botulism spores that a baby (under 2 years old) cannot tolerate. I don't mean to scare you, but it can be fatal.
To a solution, it's hard because she doesn't have enough water. Formula, even breastmilk, isn't always enough water for an infant. If she won't drink it straight, you can add a little sugar. (I don't like refined sugars but in this case, she really needs the water.)
Prune juice, straight, can be given any time to push things through. It will soften the stool also. It is actually good for a baby as it has fiber that is healthy for her digestive tract. It's also terribly sweet tasting so babies usually like it. (Don't worry about her getting too much sugar as it is a complex sugar because of the fiber.) The only problem with it is it will stain if she dribbles... so make sure she's got her bib on :)
God bless!
M.