Last Summer, I used a prepared container soil mix for my terrace container garden (Magic Soil). I pulled out the plants in the fall and stored the containers and the soil in the garage.
Would it be advisable to re-use the same soil this year or should I pitch it out and start with a new batch?

I would use new soil the soil you have in the containers is probably full of roots from last years plants. Try using Miracle soil it's the greatest stuff. Good luck and have fun planting.

All the nutrients have been used up. Plus there is a chance of bacteria growing in the old soil.each season you should always use new soil.