I'm not one to try this due to it's amazing cheeziness, but monosugoku kawaii! might get you a smile. Even if she knows how cheesy it is, it's bound to get a Japanese-learner to smile, I'm sure.
If I was talking to a native speaker (ie. my fiancé), I'd just say kyou mo kawaii ne
which usually goes down okay (it mean's "you look cute today too").