Book Identification - Human agent trapped by aliens and trying to escape

What is the name of the book or author in a science fiction novel in which:

Humanity discovered a means of teleporting between worlds and has established a number of colonies or outposts. However, humanity has lost contact with one of these outposts.

An agent is sent to planet that is out of contact.

He awakens in a high tech prison cell. He spends a great deal of time attempting to discover a means of escape and eventually accidentally kills himself in trying to escape.

After which he appears in the high tech prison cell again.

Over the course of the book he discovers that:

• Aliens have taken over the base


• His teleportation signal/information was recorded.


• The aliens are using his teleportation information to generate new copies of him after the old one dies.


• He slowly tries to learn a little more on how to escape and pass that information on to future incarnations of himself.

He eventually escapes from his cell. I'm vague on this but I think he rescues one or a small number of the base personnel and gets them back to the teleportation unit.

As he prepares to teleport back to Earth, he realizes that the teleportation unit will record this version of him - which the aliens will use to generate another version of him to torture and learn more information from.

He hopes that "he" will not be the one stuck behind.

After teleporting he realizes that until those aliens are defeated, a version of himself will remain the plaything of the aliens to torture or do anything else they desire.