Need to make my character glide.

Unity Engine
1

So my problem is that when my character is gliding after pressing space, I want to be able to press space again to stop gliding and I don’t know how.

using UnityEngine;
using System.Collections;

[RequireComponent (typeof (Controller2D))]
public class Player : MonoBehaviour {

    public float jumpHeight = 4;
    public float timeToJumpApex = .4f;
    float accelerationTimeAirborne = .2f;
    float accelerationTimeGrounded = .1f;
    float moveSpeed = 8;
    public bool IsGliding = false;
    float Fallspeed = 4;

    float gravity;
    float jumpVelocity;
    Vector3 velocity;
    float velocityXSmoothing;

    Controller2D controller;

    void Start() {
        controller = GetComponent<Controller2D> ();

        gravity = -(2 * jumpHeight) / Mathf.Pow (timeToJumpApex, 2);
        jumpVelocity = Mathf.Abs(gravity) * timeToJumpApex;
        print ("Gravity: " + gravity + "  Jump Velocity: " + jumpVelocity);
    }

    void Update() {

        if(IsGliding && velocity.y < 0f && Mathf.Abs(velocity.y) > Fallspeed)
        {
            velocity = new Vector3(velocity.x, Mathf.Sign(velocity.y) * Fallspeed);
        }
       
        if (controller.collisions.above || controller.collisions.below) {
            velocity.y = 0;
        }

        Vector2 input = new Vector2 (Input.GetAxisRaw ("Horizontal"), Input.GetAxisRaw ("Vertical"));

        if(Input.GetButtonDown("Jump") && !controller.collisions.below)
        {
            GlideStart();
        }
       
        if (Input.GetButtonDown("Jump") && controller.collisions.below) {
            velocity.y = jumpVelocity;
            GlideStop();
        }

        float targetVelocityX = input.x * moveSpeed;
        velocity.x = Mathf.SmoothDamp (velocity.x, targetVelocityX, ref velocityXSmoothing, (controller.collisions.below)?accelerationTimeGrounded:accelerationTimeAirborne);
        velocity.y += gravity * Time.deltaTime;
        controller.Move (velocity * Time.deltaTime);
    }

    public void GlideStart()
    {
        IsGliding = true;
    }

    public void GlideStop()
    {
        IsGliding = false;
    }
}
2 
[LIST=1]
[*]if(Input.GetButtonDown("Jump") && !controller.collisions.below&& IsGliding ==false)
[*]        {
[*]            GlideStart();
[*]        }
[/LIST]
if (Input.GetButtonDown("Jump") && IsGliding ==true) {
            velocity.y = jumpVelocity;
            GlideStop();
        }