Posted: 09/11/2013 at 22:04
I sometimes leave the old compost in the bottom half of the pot and replace the top layer with fresh stuff to get the new plants off to a good start. The rest of the old compost can be used as a soil conditioner elswhere in the garden.
And listen, there is no need to apologise for asking a simple question. As someone else has said, the only stupid question is the one you are too afraid to ask.
Every time someone asks a basic question, lots of other people read the answer and think, "Ooh, I'm glad he asked that, I was wondering too!"