Im trying to constantly increase the variables "pet.petage" and "pet.pethunger" then save and load them but they only increase once

Im trying to constantly increase the variables “pet.petage” and “pet.pethunger” then save and load them but they only increase once:
code:
Kangaroo.xml

<Pet>
<petname></petname>
<pethunger></pethunger>
<petage></petage>
</Pet>

Pet.cs

using System.Xml.Serialization;
[XmlRoot("Kangaroo")]
public class Pet
{
    [XmlElement("petname")]
    public string petname;
    
    [XmlElement("pethunger")]
    public float pethunger;
    
    [XmlElement("petage")]
    public float petage;

}

XMLDeserializer.cs

using UnityEngine;
 
public class XMLDeserializer : MonoBehaviour
{
    private void Start()
    {
        
    
    }
    void Update() {
        Pet pet = XMLOp.Deserialize<Pet>("Kangaroo.xml");
        print(pet.petname);
    print(pet.petage);
    print(pet.pethunger);
    }
    
}

XMLOp.cs

using System.IO;
using System.Xml.Serialization;
 
public class XMLOp
{
    public static void Serialize(object item, string path)
    {
        XmlSerializer serializer = new XmlSerializer(item.GetType());
        StreamWriter writer = new StreamWriter(path);
        serializer.Serialize(writer.BaseStream, item);
        writer.Close();
    }
    	public static T Deserialize<T>(string path)
	{
		XmlSerializer serializer = new XmlSerializer(typeof(T));
		StreamReader reader = new StreamReader(path);
		T deserialized = (T)serializer.Deserialize(reader.BaseStream);
		reader.Close();
		return deserialized;
	}
}

XMLSerializer.cs

using UnityEngine;
using System.Xml.Serialization;
using System.IO;

public class XMLSerializer : MonoBehaviour {
     

     void Start() {
         
          
     }
     void Update() {
         
         Pet pet = new Pet();
         XMLOp.Serialize(pet, "Kangaroo.xml");


         pet.petname="petname";
        
       
           pet.petage += .6f;
        pet.pethunger++;
       
        
        


        
     }
}

It looks like you’re creating a new pet object each update, rather than updating the first one. ,Based on a quick read of your code, you are creating a new pet object each update, rather than updating the first one.