How many seasons can I use the potting mix in my earth box?

The earth box people say to replace the mix after 2 seasons. Is this necessary? Mine are filled with Miracle Grow potting mix and have been used for 2 seasons.

If I need to replace it, what would you recommend using?

Ive never changed mine, I figure with the mix that comes out with the roots, and that having to be replaced..Im good. I cant even imagine dumping all that mix out and starting over.

Do you plant in the spring and fall as well?

I've just been planting one long summer season. The tomatoes and eggplants yield really well up to the first frost in October.

I used my Jungle Growth for at least three seasons adding more as I need it but now I've switched entirely to coco coir with excellent and clean results.It is fresh and clean and easier to work.

This is what the coir looks like and all my veggies and flowers love it.