Can the emergency slide be re-used after it has been deployed?
Sure. In fact, the emergency slides have to be removed from aircraft and tested periodically under present regulations.
According to Lufthansa Technik:

Under current regulations each emergency escape slide must be removed from the aircraft every three years and checked in the workshop.
The slide is tested by &quot;flat firing&quot; the slide on the floor; the test confirms that the slide inflates properly within two to ten seconds, depending upon the aircraft and type of slide.
The inflated slide is also checked in the workshop at over-pressure to test that seams retain their integrity under extreme loads. The slide is also tested for its ability to remain properly inflated for several hours.

This testing cycle varies according to the OEM/operator. For example, according to Boeing, the B747-400 slides have a 12 year testing cycle. In addition, they are checked regularly depending on various factors like its age etc. According to Udo Janssen, Lufthansa Technik’s director of emergency equipment,

At approximately 15 years of age, the first signs of aging appear with the materials—porosity of the fabric, seam peal, or pack board delamination. That is the reason why, after 15 years, the OEMs change the inspection schedules from three-year intervals to yearly cycles.

During these tests, the slides are usually inflated either fully or partially. So, the undamaged slides can certainly be reused.