If some of the roots rotted, then you will also lose some of the top growth. You might also lose some top growth due to the roots that were torn/broken off when the plant was removed from its old pot.
Although it may be just my own opinion, I don't think any plant suffering from root rot should be repotted into a larger pot. All that will do is surround the roots with a greater volume of soil, which would take longer to drain properly. That will just contribute to more root rot.
What kind of soil did you use when you repotted? Cactus mix is on the alkaline side and usually doesn't have much in the way of organic content. It wouldn't be appropriate for your plant, which prefers a rich soil, either neutral or mildly acidic.
All in all, there must be healthy roots to support the top growth. Root rot does not automatically stop just because the plant is repotted. As RG mentioned, it's a fungal infection, and it may continue to progress. This is especially true if the pot size is too large, the soil fails to drain quickly enough, or the pot is replaced in its saucer or tray before all excess water has drained off. A plant can survive root rot, but it usually takes quite awhile for the new roots to grow. In the meantime, there will definitely be a loss of top growth.