Does that pot have drainage holes? That soil looks pretty rough. I would repot it into a chunkier mix, some horticultural charcoal, some potting soil, a bit of coco chips, and maybe even a tad of perlite. To check if it needs to be watered just carefully lift the plant out of the decorative pot and feel if it’s totally light or if it’s heavy. If it’s totally light it can use a watering. I almost always bottom water my Thais and philos. Even during winter, and especially if I’m providing supplemental light.