Hi there. It's always a topic for discussion, but the principle is good. In an organic system with enzymes and worm compost, we no longer consider the soil as just a disposable medium, but as an ecosystem. As long as the physical structure of the soil doesn't collapse, you can go through dozens of cycles. 1. Why not change the soil? The Soil Trophic Network: The older the soil, the more stable and effective the colonies of beneficial bacteria and fungi (mycorrhizae) are. By changing the soil, you start from scratch and lose that natural "immune system." The Enzymes: By providing them throughout the cycle, you help break down the dead roots from the previous cycle to turn them into nutrients. This prevents the soil from suffocating. 2. The regeneration strategy (The key point) The soil doesn't wear out; it depletes its nutrients. Here's how I would manage the cycles: Worm compost addition: Your top-dressing every two cycles is a good base, but for the long term, I would add a bit between each cycle. Mineral amendments: After 3 or 4 cycles, the soil may lack trace minerals. A bit of basalt, rock dust, or dolomite lime helps maintain pH and mineral structure. The "No-Till": Ideally, you shouldn't even turn the soil. You cut the plant at the base, leave the roots in the pot, and just replant next to it. The enzymes will do the rest. 3. When should you really change? There are only two valid reasons to throw away your soil: Salt accumulation: If you've mistakenly used mineral fertilizers, the soil becomes toxic. Massive infestation: If you have root pests (like root aphids) that keep coming back every cycle. My analysis: If you stick to your program (enzymes + worm compost), you can easily last 3 to 5 years (or 10-15 cycles) without changing the soil. The only thing you'll do is add a bit of organic matter on top to compensate for what the plant has consumed. I hope the answer isn't too long. Have a great day!