I know it sounds weird but it is very old ayurvedic remedy to hide upper lip hair naturally. Both of these ingredients have bleaching and skin lightening property and they are perfect combination for upper lip hair.
What you need to do:
You need some soaked lentils. Mix potato juice and lentils along with some lemon juice and honey to make a mixture. Apply this mixture over your upper lips followed by rinsing off with normal water after 30 minutes or so.