Make a backup of the directory C:\ProgramData\QlikTech\ManagementService\QVPR. That's where the task repository lives (if your are using the XML-version). There is also a QMC page where you can make repository backups automatically. See QMC->System->Setup->Management Service->Repository->Backup settings.
On the new machine, restore the task repository from the backup you made and put it in the same location.
Maybe you should consider storing the repository in a SQL Server DB (the free editiion will probably do very well). In that case, it would be a matter of simply disconnecting the old server from the DB and connecting the new one.