Rhubarb

I've got a very old rhubarb plant which until this year has always been quite good, but this year it barely broke through the ground.  It was here when we bought the house 14 years ago and I've never done anything with it!  Just wondering what to do about it as I saw on Jamie Oliver at Home that they dug up and divided a plant.  Can I do this or should I just buy a new plant?  Also, if I should divide it up etc when is the best time to do it? 

When you dig 'un up you will find that an old crown will be a fairly extensive lump and the middle bit is likely to be rather woody and weary.  Chop the middle out and ditch it, save the bits from the outside that still seem to have a bit of life in 'em and replant with a good feed as Ice recommends.