Plant is a few months old but I recently repotted it to a bigger pot. There is new leaf growth but some of the older leaves are browning at the tips. Plant has lots of indirect sunlight, I water it every week or so, and occasionally spray its leaves with water.
Maranta likes high humidity in the air, and the lack of that is probably why some leaf tips are browning. Try misting every day, or grouping it with other plants, or you can set up a pebble tray - this involves a tray that's bigger than the pot so it sticks out at least an inch all round, fill it with pebbles kept half topped up with water with the plant sitting on top of the pebbles, without actually sitting in the water. Evaporation from water in the pebble tray increases the humidity around the plant. Further info here https://www.gardeningknowhow.com/houseplants/prayer-plant/maranta-prayer-plant-peacock-plant.htm