If any program is capable of conversion or export of .notebook files to .xbk files, it would be SMART Notebook learning software. This is because both of these file types and proprietary and only used in the original software and that means rarely supported in 3rd party programs. Whenever the conversion is actually possible, could not be reliably verified.
Convert SMART Notebook document to SMART Notebook data file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert xbk to notebook on Windows
A collaborative learning software
Convert from xbk 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.