Canvas Slider Max Value / High Value Help

I have a script where an object on collision updates the max hit points for the player. The value goes up but the maxValue on the slider does not go up.

I have added the "using unityEngine.UI"

but I cannot figure out the reference to the max value. How can I update the slider...

Object in project Canvas

H

ealthBar

 LevelManager.cs
    void HealthIncrease(int exthealth)
     {
         LevelManager.instance.maxHealth += exthealth;
         LevelManager.instance.healthBar.SetHealth(LevelManager.instance.currentHealth);
 
 
 healthbar.cs
 public class HealthBar : MonoBehaviour
 {
 
     public Slider slider;
 
     public Gradient gradient;
     public Image fill;
 
     void Start()
     {
         slider.minValue = 0;
         slider.maxValue = 7;
     }
     public void SetMaxHealth(int health)
     {
         slider.maxValue = health;
         slider.value = health;
 
         fill.color = gradient.Evaluate(1f);
     }
 
     public void SetHealth(int health)
     {
         slider.value = health;
 
         fill.color = gradient.Evaluate(slider.normalizedValue);
     }