Most of the attractions on this itinerary are accessible by ferry or boat. You can take a ferry from Split to Hvar town, and then take a boat tour from Hvar town to the Blue Cave. The Game of Thrones Tour in Dubrovnik is a walking tour.
The costs of the ferry from Split to Hvar town will range from 100-150 HRK, and the costs of the Blue Cave tour will range from 200-300 HRK. The travel time for each of these journeys may vary depending on the time of departure and sea conditions.
If you have more time, consider visiting other attractions such as Plitvice Lakes National Park, Zagreb city, or Krka National Park. If you have less time, you can skip the Blue Cave Tour and enjoy more time in Hvar town or Split. Remember to wear comfortable walking shoes as most attractions require a lot of walking. Also, carry some cash and a water bottle with you while touring.