I agree that context is important - I'm playing devil's advocate a bit here (which should be obvious) - but do you re-review it then? If PJM was, for argument's sake, an 8/10 when it released, is the quality of the game diminished now?
I suppose my question is: Is Pixeljunk Monsters a worse game, than when it was released? My answer would be no.
But is Pixeljunk Monsters a better game with this release? Depends on how you value the additions vs the time it's been available. I'm not sure it's worth £6 more.