Re-using old compost

A question about : Re-using old compost

I'm so dumb that I have always re-used old compost for new plants in outdoor containers. I had no idea there was anything wrong with that!

I currently have a lot of outdoor pots full of compost remaining after dead plants have been removed. When a friend saw that I'd kept the compost, he said you must never re-use it, as it is devoid of all nutrients. Duh!

My questions:

(1) is he right?

(2) can I make any use of this old compost or must it all be thrown away?

(3) is it possible to treat old compost with some kind of feed, fertiliser, whatever, to reinstate the nutrients?

Many thanks in advance and apologies for my ignorance, which I am sure some of you find painful to read :-)

Bundly

Best answers:

• I would re use it just add fertiliser granules to it.
• No
  Yes
  You could, or just use it as a mulch .
• I wouldn't reuse compost that had grown tomatoes in for another tomato crop but there's no reason not to use it for other crops in pots or flowering plants.
  As said above, you'll need to replace the fertilizer which will have been used up.
• Mine goes in the compost bin and gets used for outdoor containers next year.
• The only other problem you might get is the transfer of pests & diseases.......
  But I have been reusing compost for years, just keep adding some fertilizer is all i do.
  HTH
• Thanks for the replies, folks. I'm sorry I don't know what a mulch is :-(
  OK so I can renew it with fertiliser, that is great! Could you name me a brand just as an example or are they all the same?
  (PS I just wanna say ... the council refuse collectors will leave behind anything that looks like garden waste, so it would be difficult for me to get rid of 14 patio container's worth of compost without them noticing. A few twigs were poking out of my black sack of kitchen waste last week and they left it outside my house and refused to take it at all :-(
  Also, without a car it's not easy to get huge bags of new compost home .... so if I can re-use, that's great!)
• So I need to just get a box of fertiliser ... granules I suppose you mean, if its slow release?