fever is not a disease by itself, it is a symptom of other infections and viruses, you should get that treated... For food, give kanji which is easily digestible and will give energy too, can also give warm soups. Give water boiled with tulsi or cumin seeds...

Hi. Give her fluids as well. Any idea why she has fever?

keep it light . soup and khichdi or whatever she feels like eating .  don't force feed . Even if she wants to have biscuits let her  .