If you want to try and regenerate a harvested marijuana plant back to a vegetative state, it is possible. You can get your plant able to be harvested again in just 6-8 weeks because of the formation of the stalk and the marijuana plant's root system. If this is your goal, change the harvest routine to only include the top third of your plant, leaving all of the healthiest fan leaves surrounding the middle of the plant. You will want to remove the buds very carefully. The lowest leaves will require you to pull off each end flower, but you will want to leave the little flowers on the rest of the branch. This will help the plant regenerate. The more of these buds you can leave on your cannabis plant, the quicker your plant will be able to regenerate. Give your marijuana plant a food that is high in Nitrogen immediately as this will help your leaves stay on the plant instead of falling off. You can either bring your plants indoors for a 24 hour light bath to regenerate, or you can use the natural sunlight during the summer to help your plant grow naturally.
You will usually see your first signs of growth in 7-14 days. You will see growth starting on the lower branches first. Once you get a small amount of vegetation, you can then move your plant into a flowering state again right away. You can also take cuttings from the vegetation of this regenerated plant to increase your viable plants. You can then grow multiple plants and have harvests recurring every 30 days. Just make sure you keep your pests outside if you are moving around plants between indoor and outdoor growing locations. Using Mother Nature to your advantage can also help you get multiple harvests off of the same plant by using sunlight to help each plant regenerate faster. Just remember to always feed lots of Nitrogen when feeding vegetating plants and keep the light on the plants as long as possible, so the plant will want to flower again very soon!