If roots are cut back the foliage mass should be trimmed to compensate for the tree's inability to move nutrients to the branches and leaves. Do not allow exposed roots to dry out. Keep them misted and if possible cover them with a slurry of soil dust as a protective coating. Plan your repotting activity around the following guidelines. In every case the decision to repot should be governed by the health of the tree, the condition of its root mass and its growing conditions.
Spring brings on a new area of concern.
Fungus and mildew diseases arrive with the warmer weather. There are a number of excellent fungicides in the market. Treat everything as if it is already infected. Benomyl is still your best bet for leaf mildew. Topical sprays of Bravo is a deterrent for pine needle cast infections as well as infections on most other conifer and deciduous trees.