Test strips are notoriously unreliable. You'd be better off with an API Master Test Kit for more accurate readings.
If your nitrates are high, a large water change and substrate vac is your best bet, with regular maintenance to follow. If the strip is correct, it looks like nitrates are 40 ppm, which isn't deadly to your fish, but at a level where a water change is called for. It looks like nitrites are 0 ppm, which is good.
What do your hardness and PH normally run? Also, what types of fish do you have in the tank? Some fish prefer hard water and base PH. If you have acidic PH fish, you can likely buy RO water at a LFS, usually for around .50 per gallon.