is there another dog/animal eating her food? some dogs just prefer to graze all day, if that is a problem you can put her on a scedual by feeding her twice a day and only leaving her bowl down for 10-20 min then take it away. no more food til next meal.
If no other animals in the house you can just put it down and leave it. At that age I would feed her 3 times a day. The only thing I don't like about leaving it down all day, is if you are not there to watch her, she could chock and die if no one is around. Some people will put their food down for 15 minutes and pick it up after that. They will learn to eat it when it is down.