It is possible but not recommended.
I'm not familiar with foxfarms but if it is like most other premix soils, it will cause you more headaches than good should you try and reuse it.
Most premix soils come with nutrients and ph buffers and the like. Most of them are surely used up, not at the level they need to be or maybe even higher than you need them since you ended in bloom.
If you were to try, it would be wise to first sterilize the soil via oven or microwave. Then flush the soil with ro or other low ppm water. Then reintroduce nutrients as needed. It can be done, but it's not for the feint of heart.
Soil is cheap, I would just buy new soil.