Combine white grape juice and sliced strawberries in a medium saucepan and bring to a boil.
Lower to a simmer and let mixture simmer for 10 minutes, until strawberries are breaking down.
Remove from heat and strain mixture through a fine mesh sieve into a heatproof bowl. Press down on strawberries with a wooden spoon to extract as much liquid as possible. Discard strawberries.
Pour mixture back into saucepan and return to low heat. Stir in acai powder, green coffee extract powder, and passionfruit powder until powders have dissolved as much as possible (acai powder is tough to fully dissolve, so there will be some granules remaining).
Remove from heat and stir in lemon juice. Return to heatproof bowl or pour into large mason jar and put in fridge to cool completely.