The only lsl to lst conversion that would make remotely sense, would be creating templates (.lst) from existing labels (.lsl) in LightScribe Template Labeler software. Templates are created so users can quickly make new labels based on predefined settings. It is not a conversion in the proper sense, more like a workflow.
Convert LightScribe Template Labeler label file to LightScribe Template Labeler template file.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert lsl to lst on Windows
A discontinued LightScribe CD/DVD media labeling utility
Convert from lsl 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.