I've never heard of the lemon juice before, but freckles are embedded into your skin, no cream or juice could take it out, unless you surgically remove it. You should keep it as it is. I'm in the same situation, I'm Asian and never had freckles when I was little, but now it covers my cheeks.

If it bothers you that much, just try covering it with make up when you go out, but try using a foundation that has a UVA/UVB on it to prevent from getting more freckles.