Hello
Thank you for your query. You can upgrade SP Page Builder pro to version 4 and install the new version on the current one. There will be no need to recreate everything, you won't lose your work hopefully.
In some cases, during an update from the old version, you may lose access to Joomla admin area. Don't worry in that case you have to manually (via FTP) delete folder: administrator\modules\mod_sppagebuilder_admin_menu - then after update all should be OK again.
In general, you can follow the steps while updating Page builder: https://www.joomshaper.com/documentation/sp-page-builder/sp-page-builder-3
And, SP Page Builder 3.x series will continue to receive security patches, updates, and compatibility support for at least the next 3 years.
Note: One of the most useful features of SP Page Builder is its backward compatibility. SP Page Builder 4 is upgradable from the previous versions.
You can check out our blog links below too:
https://www.joomshaper.com/blog/sp-page-builder-4-0-alpha-1-a-fully-visual-joomla-page-builder
https://www.joomshaper.com/blog/joomshaper-plan-for-sp-page-builder-3-x-series
https://www.joomshaper.com/blog/sp-page-builder-4-0-alpha-2