You can reuse your post by reposting it. To do that:
Open your calendar section from the menu bar on the left.
Choose the accounts in the upper left corner.
Scheduled and published posts for previously chosen accounts will be displayed.
Choose the one that you would like to repost and click on the three dots button in the upper right corner of the post.
The drop-down list will be shown. Choose the Repost to… button by clicking on it.
Now, the post you would like to repost will be displayed in the creating mode again and you will be able to edit it or schedule to different accounts.