Timer for enemy up and down java/libgdx

Question

I want to make the selected enemy increase position.y by 1.0 and after 1.5 seconds return to the original position. I already use a timer of 2 seconds because I need to select a random enemy every 2 seconds, and then increase the position. My code:

public static int getRandomElement(int[] arr){
    return arr[ThreadLocalRandom.current().nextInt(arr.length)];
}


public static int[] deleteRandomElement(int[] arr, int index){
    int[] arr_new = new int[arr.length-1];
    for(int i=0,k=0; i<arr.length; i++){
        if(i!=index){ 
            arr_new[k]=arr[i];
            k++;
        }
    }
    return arr_new;
}



public void makeEnemies() {
    enemies = new Array<Enemy>(9);
    enemies.add(new Enemy(new Sprite(new Texture("mysterio.png")), position1));
    enemies.add(new Enemy(new Sprite(new Texture("ironman.png")), position2));
    enemies.add(new Enemy(new Sprite(new Texture("rhyno.png")), position3));
    enemies.add(new Enemy(new Sprite(new Texture("venom.png")), position4));
    enemies.add(new Enemy(new Sprite(new Texture("sandman.png")), position5));
    enemies.add(new Enemy(new Sprite(new Texture("scorpion.png")), position6));
    enemies.add(new Enemy(new Sprite(new Texture("octopus.png")), position7));
    enemies.add(new Enemy(new Sprite(new Texture("mj.png")), position8));
    enemies.add(new Enemy(new Sprite(new Texture("ned.png")), position9));
    
    
}

private void makeAnimation(){
    enemies.get(RandNumPick).position.y += 1.2;  //up

    //enemies.get(RandNumPick).position.y -= 1.2;  //??down
    
}

@Override
public void show() {
    
    
    BackgroundLevel1 = new Texture("BackgroundLevel1.png");
            
    //spawn
    position1 = new Vector2(115,180);
    position2 = new Vector2(365,165);
    position3 = new Vector2(535,165);
    position4 = new Vector2(793,295);
    position5 = new Vector2(793,450);
    position6 = new Vector2(735,450);
    position7 = new Vector2(485,540);
    position8 = new Vector2(900,440);
    position9 = new Vector2(365,285);
    position10 = new Vector2(365,300);
    
    
    timerspawn = 0;
    timerbonus = 0;
    
    
    RandNumPick = getRandomElement(numpersonaggi);

    
    makeEnemies();
}    

@Override
public void render(float f) {
    Gdx.gl.glClearColor(0, 0, 0, 0);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

    
    if(TimeUtils.nanosToMillis(TimeUtils.nanoTime()) - timerspawn >= 2000){
        timerspawn = TimeUtils.nanosToMillis(TimeUtils.nanoTime());  

        //Copy of array without the random number (so no two random ones will be alike)
        int[] numpersonaggi_new = deleteRandomElement(numpersonaggi,RandNumPick);
        
        
        RandNumPick = getRandomElement(numpersonaggi_new);
        
    }
    
    makeAnimation();
    
    
game.batch.begin();
    
    //Background
    game.batch.draw(BackgroundLevel1, 0, 0, SpiderEnemies.WIDTH, SpiderEnemies.HEIGHT);

    //Creo un ciclo for per stampare gli enemy (sprite)
    for (i=0;i < enemies.size; i++){
        Enemy enemy = enemies.get(i);  
        game.batch.draw(enemy.sprite,enemy.position.x,enemy.position.y,100,100);
    }
    
game.batch.end();
}