Is there any way to reconnect an external drive...

[rockinrocker]

after it's been ejected without physically disconnecting and reconnecting?

Or rebooting?

Thanks.

 

[zepman]

Yes, you can mount it again using Disk Utility.

 

[maflynn]

Disk Utility is the easiest way, or just unplugging and plugging back it

 

[Fishrrman]

Try something called "Semulov" ...

 

[simsaladimbamba]

Try something called "Semulov" ...

Yep, just wanted to add that little application too.
It is a small utility sitting in the Menu Bar and it is written by a member of this board. I can only recommend it.