You can start new crops in your Auk any time you’d like, here's how you do it:
Empty the pots of plants and soil, and clean the pots and the cultivation board with some soap and water (or put it in the dishwasher if you want to)
Reset your Auk by holding the light button for about 30 seconds until you see all the lights on the display turning off.
Put the plant chip on as you did when you first started up your Auk.
Auk will start up in the first plant phase and do the initial watering after 30 minutes, so you should make sure you are done with all the pots before starting it up.
As easy as that :)
If you just want to replace some of the plants in your Auk and keep other grown plants, you can find instructions for it here.