E. Red Ceder Juniperus Vir. Progression question

I have this common juniper (not a common bonsai subject) which was dug and potted in a mortar tray and filled with turface four-ish years ago. I’m planning on cutting the escape roots this weekend and work new soil in on one side.
I’m not super confident with Juniper root work but I’m getting there. So does this sound rational or should I do more. Zone 7 The tree has healthy foliage and backbudding to some extent. Easy six-inch Nabari.

Do the roots escape out the bottom of the tray? It’s hard to tell from the pic.

As for repotting, I’d consider doing it in early spring after the cold weather has passed. I’m not as familiar with the variety so I don’t know if there are additional considerations.

Yes sir, the roots escape the tray into the ground. I’ve cut a few already finger thick. I would like to move it closer to my other trees or at least turn the future front to the son.
Also I was in the mind set that fall season is an opportunity to collect or mildly abuse a juniper. Since our winter is pretty mild and spring is short. I live in peach tree country. Maybe I’ll just cut the ground roots and top dress. What do you guys think?
The J. Virginiana has foliage I believe to be similar to J. Rocky Mountain. It grows like a Christmas tree in rock hard red clay.

The amount of work you do now will inform how much protection the tree will need over winter. In general, I try to keep trees as strong as possible going into the dormant season, especially if they’re exposed to occasional - or frequent - freezes.

Well late spring i’ve cut the escape roots cut 1-2 inches of old soil around the perimeter of the tray. Since the tree isn’t showing any stress. I’m going to approach graft it’s native branches and reduce the dimensions of the tree being careful not to damage the lifelines I need for the approach graphs to take. The tree is large enough for the juniper V. foliage to work and look correct in scale, although I am thinking about grafting a blue needle Juniper foliage. I have shimpaku stock but I like to try something different. Thoughts and opinions welcome.

Your approach is more aggressive then i would take. It will be interesting to see how well the tree does.