The bike doesn't "need" to be repainted, but I can assure you that you are leaving a door wide open for her to not like it from the start, and that - even if she does accept it - she will find other, unrelated "reasons" to not like the bike. Presuming this is an option, I would involve her in selecting the color(s), and then ensuring someone with adequate skills and facilities performs the painting and any finishings. While it might not hurt to have a couple suggestions in mind if she's drawing a blank, let the process (at least as far as selection goes) be hers, and she will have an attachment to it - possibly even before actually giving it a test ride.

If she does give the frame a test-ride before you get it refinished, be sure to put better tires on once it's been painted, as this gives a built-in advantage when the ride quality of the finished product is assessed.