u/1Lopsided_Rutabaga

Help! I’ve just inherited this 35+ year old hibiscus from my late grandmother. I noticed when it was brought inside for the winter (I live in Wisconsin) that the roots had started growing out of the bottom of the pot.
I was told to wait until spring when it goes back outside to repot, but I am not sure how to go about that.
If anyone has any tips on how to keep this plant thriving I would appreciate it! (OC)