S.L.
Why are you asking her? I have 4 daughters and I can tell you without a doubt that if you tell her that you love her, eventually she'll say it to you. People like to share affection on their own time table. It would be disconcerting if my husband walked up to me and asked me often if I loved him. Why would a child want that question any more than an adult? It makes me feel as if it's going to teach her to have low self-esteem and to always be looking for confirmation of a persons feelings for her.
It's also possible that she likes the reaction you give her. She might feel it's a game. She's way too young to understand how anything she says or does makes someone else feel. Children are way older, 5-8 years old before they can even begin to have real empathy towards others.
Also, giving a child EVERYTHING they ask for isn't always the most loving thing to do. Children don't always know what's good for them and what they want may do more harm than good.