There is an easier way, just do not remove and re-add the control. Here is what I do when I deploy a control, and then I need to change it:
1. Create a user control
2. Define it in the control toolbox. At this point, I am able to drag and drop it on the page.
3. I make a change on the control in visual studio, and I am seeing the change in the Sitefinity page as well. No need for removing and re-adding the control
If you need to deploy the user control on a remote server, just upload the files and overwrite the old ones.
I hope that I am not missing something.
All the best,
the Telerik team