It appears that both .npl and .ndw files originate from Allplan Engineering and if any program can somehow convert / export one to another it would be this program. We couldn't find anything specific about this npl to ndw conversion, so if you are looking for something particular, please let us know in the discussion below.
Convert Allplan plot layout file to Allplan drawing file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert npl to ndw on Windows
A CAD construction software
Convert from npl file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.