If you’re round the south side of Loch Morlich you can also take the higher track. You should find a mass of blaeberries as trail food 🙂
Also – head along the side of the campsite, take a left at the junction and you’ll end up at the iron bridge. From there, you can double back on yourself then towards Loch an Eilean. Go clockwise round it if you don’t mind a couple of rougher bits (including a narrow bridge) or anti-clockwise for shorter/smoother. Take the signposted track away from the car park (right, up a wee hill) and you’ll end up back at Rothiemurchus.
You could also head through Aviemore along the NCN7 and end up in Boat of Garten. The Gallery does good soup and cake.