On that bike, with that stem, the bars are already as high as they can go. You can't go higher because the stem is already at the top of the fork. If the stem is angled down (hard to tell from the photo) you could get a bit more rise by inverting it, but since it's a small angle (if any) inversion won't buy you much.

However, there are stems that have different angles. If, for example, you were to get a 17° (73°) stem and mount it angled up it would rise at about 34° raising the bars by roughly 5mm for every 10mm of extension.

Offhand I don't know of stock stems with steeper angles but there probably are some out there, or you could have a builder make you a custom stem with a high rise ratio.