I use Ginabot.
And there's a way to configure your settings to include when a person resteems your post.
It's quite easy if you go to https://steemdb.com/
1. Type in your username here:
2. Then go to the Social tab and drop it down and select 'Reblogged':
The Reblogged option will show a complete history of your posts as they were resteemed in the timeline. It will also show who resteemed which posts.
Note: If you go to the Activity tab, then you can select Reblogs to see the posts that you have resteemed in the past.
It's quite very easy,just as you set notifications on ginabot to know when someone sends you steem or SBD,when someone mentions you in a post,you can set the notification for you to know when someone resteems your post.
I do know if my post get resteemed by checking on my notifications on busy.org. #busy is one of the best dApp I can't do without using everyday because it notifies me if anyone resteems my posts.
I think there are also other ways of knowing if your post got resteemed by setting up ginabot on Discod or you make use of steemd.com and I think the latest @esteemapp also works.
Thanks for reading and I hope this helps.