Incremental export/import will shorten the time.
But remember during incremental backup it will take backup of modified table, not only modified records.
Suppose one row has been added into a table after full backup, then during incremental backup the whole table will be backed up again. It is again time consuming one.
During import first you apply full backup and while applying incremental backup it will delete the table and reimport the table from incremental backup
you have to check the Compatibility Matrix for Export And Import Between Different Oracle Versions