How to reset all NLP's settings in Lightroom?

Sometimes I would like to reset the conversion done by NLP to a negative within Lightroom.
That means that I would like to be able to undo all settings done by “Convert negatives” and further on “Tones”, “Brightness”, “Contrast” etc. so that I get back to the negative.
Actually I have to remove the image from the Lightroom catalogue and import it again to be able to use
NLP again with different settings.

Is there an easier way to achieve the same result?

Thanx and best regards