The plants are supposed to live in the unit until their natural life cycle ends. However, if you wish, you can transplant them to a bigger pot and grow the plants like a regular gardener - add enriched soil mix and remember to water them. You will also need to remove all the plastic around it. The nutrients in the smart soil will last for 1 year but if you really want to transplant the plants, you should do it before their natural life cycle is up.
The plants in the Smart Garden generally last for about 2-6 months, depending on the plant.
Take the pods separately out from the unit. Remove the pod from its white plastic case - first remove the U-shaped lid, then the plastic cup and then put the plant (yes, the soil as well) in regular soil and in a bigger pot.