An 18 month absence from the radio hasn't done much for my CW skills. At first, very rusty yet after a few minutes, it starts coming back. I guess it's a bit like learning to ride a bicycle, one you can do it, you never forget.
As well as listening to CW on the various bands, one of the ways to brush up on your CW is to use a contest simulator.
I came across Morserunner a few years back and it's a novel way of listening to morse. It basically simulates operating in a CW contest and you just use the function keys on the PC keyboard to control everything. As it is all off-air, there is no pressure and you can make as many mistakes as you like.