campfire/Assets/Scripts/AssetModificationProcessor.cs

using UnityEditor;
using UnityEngine;

public class FGAssetModificationProcessor : UnityEditor.AssetModificationProcessor {
    static string[] OnWillSaveAssets(string[] paths) {
        foreach (GameObject obj in GameObject.FindGameObjectsWithTag("Generator")) {
            Lorax Lorax = obj.GetComponent<Lorax>();
            Lorax.DestroyGenerated();
        }

        EditorApplication.update += RefreshScene;

        return paths;
    }

    static void RefreshScene() {
        EditorApplication.update -= RefreshScene;

        foreach (GameObject obj in GameObject.FindGameObjectsWithTag("Generator")) {
            Lorax Lorax = obj.GetComponent<Lorax>();
            Lorax.DestroyGenerated();
            Lorax.Generate();
        }
    }
}