In the great words of someone's name I can't remember "it's better to regret doing something than regret not doing something".
Robbo, if you honestly think you've got a bit left in the tank, look after number 1 and pursue your career with another club if the Dees are not interested in you going forward.
If for example, the Dogs pick you up but you only manage a couple of games, at least you can say you gave it a crack rather than die wandering.