I think the vine colours could be updated pretty simply by removing the brightest shade from the floor vine tiles to bring them more in line with the light/dark scheme used by the walls/floor.
I just noticed that one wall (middle-left) is a tile shorter than the others. Is that on purpose?
Torches would be a good fix, or adding some pipes with an orange/red/yellow hue could also work, and would make sense for a sewer.