what should i do to coax my nesting cockatiel to eat more?

[this is a random name]

she rarely even comes out of the nestbox where she has already laid two eggs, and when she does, all she does is gets a drink of water, walks over to the food dish, looks inside of it and goes back to her eggs. i don't know if she is looking for a specific type of food or something, because i'm feeding her what i always feed them, but she seems to be looking for something else. is there anything i can add to her food that will make her want to eat, because i'm worried she won't have enough energy to take care of her babies when the time comes... and i don't know why she's doing it this year, usually she eats just fine when she comes out of her box