Reheating a Pretzel

easiest way is to mix it with the sauce and heat both up together. Usually I'd do this in a pan, but you could use a microwave.

If you have to heat the pasta up on its own, what I usually do is do it in a pan and add a little boiling water, just a couple of tablespoons, enough to stop it sticking, and keep stirring until its warmed through. If it starts to stick add a little more water.

You could do this in a microwave I'd bet, but I don't have one.

As this basically got answered through questions in the comments, I'll collect up all of the various problems that might help prevent the sogginess:

1. After frying, allow the croquettes to cool on a wire rack, so they don't get moist as they give off steam.
2. Reheat first at a lower temperature to heat through, then turn it up the temperature to regain the crunch & get any extra browning.
3. Make sure when reheating that they aren't packed too tightly, and if possible, heat on a wire rack rather than a pan.
4. If reheating in a small but tightly-sealing oven, try cracking the door slightly so as to prevent humidity buildup.

(anyone who has any other suggestions, feel free to add 'em)