Quote Originally Posted by tevfik
Are you going to add perlite in to this?
If so, first prepare your medium by adding %20 to %40 perlite in it. You can spray perlite with water to prevent dust during the work.
You may want to flush new compost with PH corrected water before use but it might not be necessary if you will be careful about watering from now on . I can suggest to use rain/deionized/distilled water for one to three watering. You can also mix those with tap water as well.

Now, after preparing the new compost, let the old compost dry out a little but not completely. Like %25 moist to handle easily. After that remove the pot. You must be able to hold the plant from the main stem. Hold the compost from the sides, lightly press and lightly roll in your hands. After that you can hold it from the stem and hit to the floor lightly. Washing out old compost is another alternative. Or you can invent your own way to do this. After old compost cleaned out from the roots (you don't need to clean all. You can do as much as you can, even %50 can be enough.) add some new compost in to bottom of the pot and press lightly (amount is depend on plants height, you can see that), after that add like half or one centimeter more but don't press. Place the roots on to compost, spread around and simultaneously add more soil around and inside the root ball. When you filled it completely, water the pot, let the compost sit and add more from top. Press lightly, water lightly for the last added compost. You're done. Wait until it gets dry for next watering.
You can't spread the roots as best as they were before, don't worry about that, just do your best.

This is just one suggestion from me for you. Before doing this, make a search, wait for other responses here and find the best way for yourself to get success.

Good luck:thumbsup:
An old bonsai techniqe. :thumbsup: You can also have a pot of warm, properly ph'd water prepared, hold the mainstem and support the bottom of the rootball, and dip (dunk) the rootball a couple of times, which will wash-away some of the soil. Don't go overboard trying to remove it all though. I'd recommend taking no more than the first inch of old soil from all around the rootball. The fewer roots you disturb, the better your chances.

Sprinkle the fresh soil over the top of the rootball, and 'bump' the sides if the container to sift it through the roots. You can use a pencil (eraser end) or a plastic pen (cap on) to gently push the fresh soil/perlite into the rootball with little damage, if the voids you created require it. Usually, unless most of the soil fell out of the rootball, this 'pushing the soil in' shouldn't be necessary.
But, be real careful with the roots. Don't fold, spindle, snap, or stretch the roots, and keep 'em moist throughout the operation.

If skittish playing with the rootball and the violent Bonsai transplant thing, you can drill a few 1/2 inch holes in the sides of your pot, which will allow more airflow. Not usually as effective as perlite, but might be an option...