I have been struggling for a couple of months now on getting an axe upgrade from Serena in the fountain. Succeeding with a new axe is at least partially a matter of luck, since on some days she doesn't even give me a chance to respond before taking my old axe and disappearing. On other days, though, it feels like I'm just making the wrong decisions in the dialog tree.
Are there any choices that I should always make? Alternatively, is there a general strategy to increase my chances of getting a silver or gold axe from her?