Scores not updated when collided the second time - unity3d

Question

Im having problem with an endless runner game. The scores are not updating after the first object collided. The script is attached to a prefab object. After the first object collided, the score updated to +100, the second object collides, no change.
void Start()
{
player = GameObject.FindGameObjectWithTag("Gameship");
YourScore = GameObject.Find("Score").GetComponentInChildren<TextMeshProUGUI>();
}
void Update()
{
}
void OnTriggerEnter2D(Collider2D collision)
{
if (collision.tag == "Border")
{
Destroy(this.gameObject);
}
else if(collision.tag == "Gameship")
{
if(this.gameObject.tag == "Reward")
{
Destroy(this.gameObject);
ChangeScore(100);
}
}
}
void ChangeScore(int changeValue)
{
this.score += changeValue;
YourScore.text = score.ToString();
}
}

Answer 1

Assuming your score is starting from zero i.e. score = 0, after colliding with Reward tagged gameObject, your code does the following:
The Score increases i.e. score += 100 -> score = 100
Updates the text. text = "100"
GameObject gets destroyed.
On destruction of gameObject, your score variable also gets destroyed,
assuming you are instantiating this object again, the whole script is executed again means score = 0, hence doing the above 3 steps over again and setting the text to 100 again which it already is.
I would suggest to use a Singleton class or just store the score variable in a different script that is not getting destroyed.

Answer 2

Currently you destroy the Object and so the scorevalue after it got triggered.
You will need an extra class with a static variable which has a score variable which you increase instead of increasing the local one.
public class ScoreHolder {
public static long score = 0;
}
void Start() {
player = GameObject.FindGameObjectWithTag("Gameship");
YourScore = GameObject.Find("Score").GetComponentInChildren<TextMeshProUGUI>();
}
void OnTriggerEnter2D(Collider2D collision) {
if (collision.tag == "Border") {
Destroy(this.gameObject);
} else if(collision.tag == "Gameship") {
if(this.gameObject.tag == "Reward") {
ChangeScore(100);
Destroy(this.gameObject);
}
}
}
void ChangeScore(int changeValue) {
ScoreHolder.score += changeValue;
YourScore.text = ScoreHolder.score.ToString();
}