Here are some options, depending on the desired effect:
For a playful rhyme:
* Swiss miss: This is a common term, though not necessarily the most respectful.
* Alpine queen: This has a more poetic feel.
* From the Alps, she's keen: This is a bit longer, but emphasizes her origin.
For a more precise rhyme:
* A Swiss girl, with a heart that's blithe: This emphasizes her nationality and uses a near-rhyme.
Ultimately, the best option depends on the context and your intended tone.