Put the kiwi, bananas and cranberries in a bowl, add the lemon juice and stir well. Put everything in a saucepan, turn on the heat. Add the preserving sugar and the fruit juice, mix everything well.
Bring to the boil once, stirring constantly, then reduce the heat until the mixture is only simmering. Simmer for 5 minutes, stirring frequently, until the fruit becomes puree - then turn off the heat.
If the jam is still too chunky for your own taste, use a normal potato masher to crush everything and stir.
Remove from heat, put 1 teaspoon of the mixture on a small plate and check whether the jam is no longer too runny. If it does, add a little citric acid and stir in.
Now pour the hot mixture into small glasses (twist-off), close immediately and allow to cool. The basement is still ideal for storage.