Here is a pic of what I described.

My thoughts is that you may be getting too much water and harming the roots so they can never really get going. My Heritage raspberries planted in the ground took off well and fruited the first year. The second year fruited like crazy and 3rd year was trying to over run the designated area. On year 4 I have a photo of 6' me behind the bush and many canes were as tall as I, and we had to increase the allowable area to 6' x 12' letting it overrun the blue berries.

The growth in the picture looks perfectly healthy to me. It is the nature of raspberries to 'walk' and they like to seek out new fresh soil to grow in. The old cane stubs will always be in evidence. I've never tried growing them in pots as it it just seems too much hassle. It is a very different business from growing them in the ground where they have space and can look after themselves.

I wouldn't worry too much about there being fewer canes this year -- three to five seems entirely reasonable for a container of that size, and you're still likely to see some new canes in the coming weeks. As for a repot, I'd wait until early next year and do it while they're dormant. At that point, a complete change of potting mix would be a good idea. For now, I'd focus on providing enough (but not too much) water and fertilizer. I've only begun growing cane fruits in pots in the last couple of years, but my experience has been that they need a steady supply of nutrients in order to thrive in the tight confines of a container.

Past years, the pots had growth all over. These

I will wait until next year but how would I repot? What part of the root mass would I keep? How would I tell the live part (vs the piece in the middle of the pot where nothing is growing. Can I separate portions of the root somehow? I have never tried to repot anything.

It isn't too much water as the media is pretty well draining.