I want to edit a sequence more than once. What is the procedure for this because the  sequence is already edited.?

You can use the snapshots feature in LRTimelapse to save a set of edits for the whole sequence, then initialize and redo the process or just reedit the keyframes and continue with the 2nd workflow row.
You can always revert back to a saved snapshot.
When exporting via LRTExport make sure to change the name of the folder, if you want to preserve the older edit.
You'll find the snapshots tools on the top right of the table and in the menu.