I'd keep the shade and ditch the valance. If you want to change the shade try a top down bottom up style. You can cover the top of the arch too if you wish.

Such lovely windows! I suggest that you replace those valances with drapery panels, flanking each window, hung high--just above the arch. This would give you an updated look while warming up that space. The right fabric would let you set the tone that you're looking for--elegant, casual, colorful, subdued, etc. Let us know if we can help--we create digital renderings on top of photos to help our customers visualize!

I would get rid of the valance too. They totally cut your windows and the room in half. Install panels above the arch, or cover it as suggested.

Asymmetrical drapery panels on decorative rods mounted above the arches.

I made these and they look great over an arched window