On 2010-08-19, Roger Tonkin wrote:
My current summer fruiting raspberries are on their last legs. Having
had them for about 15 years, over this last few years they have been
poorer and poorer, culminating this year in a small crop, and very few
new canes for next years fruit.

I plan to dig ut (may be) half the row, but due to lack of space I've no
where else to plant new canes, except where the old ones come out.

1) Am I asking for trouble replanting in the same spot?

Yes. The reason the canes are fading is more than likely becuase of a
build up in disease.