Help! My plant is growing mold. How can I save it?

I just repotted a healthy (but root-bound) rubber plant. When I was pouring in the fresh soil, I noticed some white stuff but didn't know if it was mold or just natural spongey white stuff. Well, now I think it's mold because the top of the soil in my potted plant is covered in a yellowish mold. What is the best way for me to re-pot the plant and ensure its healthy future? Can I scrape the mold off the top of the dirt or do I need to re-pot entirely? And, any suggestions for repotting a very root-bound plant?