I tease out the old roots and use it at the bottom of pots with fresh compost on top......make sure it bug free as well as weed free though

I do the same as Pam, or use it as a mulch on the borders.

I usually add it as a mulch to the garden borders.

I use it to mulch or add to the compost heap.

I use it as a soil improver on poor bits of the garden or mix it with new compost if I'm running out or feeling mean - but add some fertiliser if you reuse it.