//for unity c#
using UnityEngine.SceneManagement;
...
SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
if (Input.GetKeyDown(KeyCode.R))
SceneManager.LoadScene( SceneManager.GetActiveScene().buildIndex ) ;
if (Input.GetKeyDown(KeyCode.R))
SceneManager.LoadScene( SceneManager.GetActiveScene().buildIndex ) ;