Will data be preserved when updating new jar and sheetster files?

The data will be preserved. When saving files as excel (as opposed to xml), data will not be lost between upgrades.

Upgrading the Sheetster.jar file and Web App files will not affect your document data. Data is stored as files in the server file system under the /media/userid/memeid/scheme, in a CMS/DMS such as Mindtouch or Alfresco, or in a relational database.

If you are using the default settings on a local installation using the file system storage, then re-installing the Sheetster installer may overwrite these files. In this case it is vital that you save or move the files stored in <installdir>/media as well as <installdir>resources/e360.* files.