manabar doesnt work

my mana doesnt regenerate and i dont know if my health regenerates because i haven't made anything to make you lose health yet.

here is my script:

 var lefthand : Transform;
 var righthand : Transform;
 var spell : GameObject;
 var spell1 : GameObject;
 var spell2 : GameObject;
 var spell3 : GameObject;
 var spell4 : GameObject;
 var spell5 : GameObject;
 var spell6 : GameObject;
 var spell7 : GameObject;
 var spell8 : GameObject;
 var spell9 : GameObject;
 var spell10 : GameObject;
 var spell4u = 0;
 var spell5u = 0;
 var spell6u = 0;
 var spell7u = 0;
 var spell8u = 0;
 var spell9u = 0;
 var spell10u = 0;
 var health = 100;
 var mana = 100;
 var dummy = 0;
 var minusmana = 0;
 var exp = 0;
 var level = 0;
 var maxHealth =100;
 var maxmana =100;
 
 
 function Start () {
 spell = spell1;
 Invoke("recharge", 0.1);
 minusmana = 10;
 }
 
 function recharge () {
 mana += 0.5;
 health += 0.1;
 Invoke("recharge", 0.1);
 }
 
 function manadown () {
 mana -= minusmana;
 }
 
 function Update () {
 
 maxHealth = level * 10 +100;
 maxmana = level * 10 + 100;
 
 if(Input.GetKeyDown("l")){
 level += 1;
 }
 Debug.Log(level);
 
 
 if(exp >= 100){
 exp = 0;
 level += 1;
 }
 
 if (mana >= maxHealth){
 mana =  maxHealth;
 }
 
 if (health >= maxHealth){
 health =  maxHealth;
 }
 
 if(Input.GetButtonDown("Fire1")){
 if(mana >= minusmana){
 Instantiate(spell, lefthand.position, lefthand.rotation);
 Invoke("manadown",0);
 }
 }
 
 if(Input.GetButtonDown("Fire2")){
 if(mana >= minusmana){
 Instantiate(spell, righthand.position, righthand.rotation);
 Invoke("manadown",0);
 }
 }
 
 if(Input.GetKeyDown("1")){
 spell = spell1;
 minusmana = 8;
 }
 
 if(Input.GetKeyDown("2")){
 spell = spell2;
 minusmana = 8;
 }
 
 if(Input.GetKeyDown("3")){
 spell = spell3;
 minusmana = 40;
 }
 
 if(Input.GetKeyDown("4")){
 if(spell4u == 1);
 spell = spell4;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("5")){
 if(spell5u == 1);
 spell = spell5;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("6")){
 if(spell6u == 1);
 spell = spell6;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("7")){
 if(spell7u == 1);
 spell = spell7;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("8")){
 if(spell8u == 1);
 spell = spell8;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("9")){
 if(spell9u == 1);
 spell = spell9;
 minusmana = 10;
 }
 
 if(Input.GetKeyDown("0")){
 if(spell10u == 1);
 spell = spell10;
 minusmana = 10;
 }
 }
 
 function OnGUI () {
 GUI.color = Color.red;
   GUI.HorizontalScrollbar (Rect (Screen.width * 0.1, Screen.height * 0.85, maxHealth, 10), dummy, health, 0, maxHealth);
   GUI.color = Color.blue;
   GUI.HorizontalScrollbar (Rect (Screen.width * 0.1, Screen.height * 0.9, maxmana, 10), dummy, mana, 0, maxmana);
 GUI.color = Color.yellow;
   GUI.HorizontalScrollbar (Rect (Screen.width * 0.1, Screen.height * 0.95, 180, 10), dummy, exp, 0, maxHealth);
 }