The tasks scheduled in the previous version of Talend Administration Center were generated via the Talend CommandLine of the same version, but you may not need to recompile these tasks with the new Talend CommandLine.
These binaries are located in a folder that is defined in the Generated jobs folder parameter of the Job conductor node in the Configuration page. In this archive folder, all generations of a specific task are stored in a dedicated sub-folder.
If you used the Export parameters and Import parameters options to retrieve your configuration settings, the path to your existing archive folder is automatically preserved.
For more information on how to visualize the generation version in the Job Conductor module, see the Talend Administration Center User Guide.
If you want to force the regeneration and did not use the Export parameters and Import parameters options, simply update the path to the archive folder in the Configuration page.