If it were mine, I would just keep it in the same container just one more year, and then contemplate about it again next year. I feel they are like epis in some sense, they like the tight feeling at the root section as long as there is good drainage and airflow at root zone.
My three hoyas has been in the same container since I got them, and they are okay, one for 3 years, the other 2 for 4 years. What I do have to provide is a good way to stake them since they are vining, so they like to latch on to something, and a stable container so they will not topple over.
