Generate new random Values

My code opens a window where the stats of a Rpg-like Item are shown, which were randomly generated, now my problem is, that I don't know how to make it so it generates a new Item after you press a button. I'm using the libgdx framework. When it comes to coding, I'm a bloody rookie, and this is pretty much my first application. Here's my code:

    package com.mygdx.test;

import java.util.Random;

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.g2d.BitmapFont;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;

public class Itemgenerator extends ApplicationAdapter {
private SpriteBatch batch;
private BitmapFont font;
Color rarityColor;
String rarity;
Random randomPrefix = new Random();
Random randomName = new Random();
Random randomRarity = new Random();
Random randomItemType = new Random();
Random randomItemLevel = new Random();
Random randomDamage = new Random();
Random randomWeaponSpeed = new Random();
Random randomStrengh = new Random();
Random randomEndurance = new Random();
Random randomCritical = new Random();
Random randomWisdom = new Random();

String [] Prefix = {"Blunt", "Sharp", "Jagged", "Grandmaster's", "Knight's", "Apprentice's","Crude", "Godly", "Flawless", "Barbaric", "Horrific", "Hiddeous", "Demonic", "Dull", "Bloody", "Holy", "Engergiced", "Fast", "Otherworldly", "Well-Worn", "Elegant","Vigilant", "Surpressing" ,"Destroying", "Vampiric", "Intimidating"};
String [] Name = {" Soulsplitter"," Axe", " Sword", " Spear", " Bow", " Longbow", " Staff", " God Eater", " Doomsday Device", " Excalibur", " Nature's Call", " Forest Spirit", " Dragon's Breath", " God's Wrath", " Buster", " Peace Keeper", " Jackhammer", " Battleaxe", " Emperor's Lance", " Tsunami", " Hurricane"};
String [] ItemType = {"Axe", "Sword", "Broadsword", "Dagger", "Bow","Longbow","Staff","Spear","Hammer"};

int index = randomPrefix.nextInt(Prefix.length);
int index1 = randomName.nextInt(Name.length);
int index2 = randomItemType.nextInt(ItemType.length);
int ItemLevel = randomItemLevel.nextInt(1000);
int Damage = randomDamage.nextInt(25000);
int WeaponSpeed = randomWeaponSpeed.nextInt(100);
int WeaponStrengh = randomStrengh.nextInt(350);
int WeaponEndurance = randomEndurance.nextInt(350);
int weaponCritical = randomCritical.nextInt(350);
int weaponWisdom = randomWisdom.nextInt(350);

@Override
public void create () {
    batch = new SpriteBatch();
    font = new BitmapFont();
}


@Override
public void render () {
    Gdx.gl.glClearColor(0, 0, 0, 1);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
    batch.begin();
    font.draw(batch,Prefix[index]+ Name[index1], 0, 300);
    if(ItemLevel<=101){
        rarity = "Common";
        font.draw(batch, rarity, 0, 280);
    }
    else if(ItemLevel<=251){
        rarity = "Uncommon";
        font.draw(batch, rarity, 0, 280);
    }
    else if(ItemLevel<=401){
        rarity = "Rare";
        font.draw(batch, rarity, 0, 280);
    }
    else if(ItemLevel<=551){
        rarity = "Magical";
        font.draw(batch, rarity, 0, 280);
    }
    else if(ItemLevel<=626){
        rarity = "Epic";
        font.draw(batch, rarity, 0, 280);
    }
    else if(ItemLevel<=736){
        rarity = "Unique";
        font.draw(batch, rarity, 0, 280);
    }
    else if(ItemLevel<=876){
        rarity = "Legendary";
        font.draw(batch, rarity, 0, 280);
    }
    else if(ItemLevel<=1000){
        rarity = "Glitched";
        font.draw(batch, rarity, 0, 280);
    }

    if (rarity == "Common"){
        font.setColor(Color.WHITE);
        }
        else if(rarity == "Uncommon"){
             font.setColor(Color.LIME);
            }
        else if(rarity == "Rare"){
            font.setColor(Color.BLUE);
        }
        else if(rarity == "Magical"){
            font.setColor(Color.PURPLE);
        }
        else if(rarity == "Epic"){
            font.setColor(Color.PINK);
        }
        else if(rarity == "Unique"){
            font.setColor(Color.YELLOW);
        }
        else if(rarity == "Legendary"){
            font.setColor(Color.ORANGE);
        }
        else if(rarity == "Glitched"){
            font.setColor(Color.RED);
        }
    font.draw(batch, "ItemLevel: "+ItemLevel, 140, 280);
    font.draw(batch, ItemType[index2], 0, 260);
    font.draw(batch, "Damage: "+Damage, 0, 220);
    font.draw(batch, "Weaponspeed: "+WeaponSpeed, 140, 220);
    font.draw(batch, "+"+WeaponStrengh+" Strengh", 0, 200);
    font.draw(batch, "+"+WeaponEndurance+" Endurance", 0, 180);
    font.draw(batch, "+"+weaponCritical+" Critical Strike", 0, 160);
    font.draw(batch, "+"+weaponWisdom+" Wisdom", 0, 140);
    batch.end();
}

@Override
public void resize(int width, int height) {
}

@Override
public void pause() {
}

@Override
public void resume() {  
}

}