Yeah I know what's the problem.
You weren't clear when you wrote request. I'm also confused :D

Okay so check this out :

     if (moneyAmount == 0)
             {
    // In plain english we say :
    // If moneyAmount is equal to 0

                 moneyAmount = score;
    // We will set value of moneyAmount to value
    // of score
             }

             else if (moneyAmount != 0)
             {
    // but we will not do that if moneyAmount value is not 0
    // instead, we will add value of score to moneyAmount value
                 moneyAmount += score;
             }

    // Also, you are writing this code in void Start() which only gets called once when script gets initialized.


Do you see the problem ? Code is working fine but your logic is wrong.

So to make this happen we can do something like this :


        int moneyAmount = 0; // We will use this to track current score
        int bestScore = 200; // Max score ever


        void AddToScore(int value)
        {
            // All we do here is we add
            // value to out score
            moneyAmount += value;
        }

        void AddOneCoinToScore()
        {
            moneyAmount++;
        }

        void GameOver()
        {
           // You can call this function when player dies

            if (moneyAmount > bestScore)
            // If moneyAmount player had when he died
            // is greater than best score
            {
                // Set best score to be moneyAmount
                bestScore = moneyAmount;
            }
        }


Now you probably have some way to check when player gets one point right ?
When player gets one coin, all you have to do is write :
    AddOneCoinToScore();
When player dies, all you have to do is call :
GameOver();

And if you want to add custom value of points to score, you can call :
 AddToScore(5);

Here's an example again :

    using UnityEngine;
    using System.Collections;

    public class add : MonoBehaviour {

        int moneyAmount = 0; // We will use this to track current score
        int bestScore = 10; // Max score ever
        float timer = 1.0f; // Debug test variable
        float DieAfter = 5.0f; //  Debug test variable

        void AddToScore(int value)
        {
            // All we do here is we add
            // value to out score
            moneyAmount += value;
            Debug.Log("Added " + value.ToString() +
                         "coin(s) to moneyAmount. Money : " +
                            moneyAmount.ToString());
        }

        void AddOneCoinToScore()
        {
            moneyAmount++;
            Debug.Log("Added one coin to moneyAmount. Money : " + moneyAmount.ToString());
        }

        void GameOver()
        {
           // You can call this function when player dies

            if (moneyAmount > bestScore)
            // If moneyAmount player had when he died
            // is greater than best score
            {
                // Set best score to be moneyAmount
                bestScore = moneyAmount;
                Debug.Log("Player Died, new high score :" + bestScore.ToString());
            }
        }

        void Update()
        {
            // This is just debug example and is not relevant
            // to your code, it just shows you how to call
            // functions
            timer -= 1f * Time.deltaTime;
            DieAfter -= 1f * Time.deltaTime; ;

            if (timer <= 0)
            {
                AddOneCoinToScore();
                timer = 1.0f;
            }

            if (DieAfter <= 0)
            {
                GameOver();
                DieAfter = 5.0f;
            }
        }

    }


![alt text][1]


  [1]: /storage/temp/37560-example.jpg

I hope that it's more clear now ?