Navigation Cocossharp and xamarin.forms

Question

I have 2 pages, In first page when I click one of the item in listview, it should navigate to 2nd page and here in 2nd page snow particles are appeared.

After that, when I click back button, as usual it goes to first page and again when I click any of the listview items it navigates to 2nd page snow particles disappear,It just show a black screen.

Here are the codes:

For snow rendering I have two classes

First one

public class SnowScene : CCScene
{
    CCParticleSnow snow;

    public SnowScene(CCGameView gameView) : base(gameView)
    {
        var layer = new CCLayer();
        layer.Color=new CCColor3B(new CCColor4B(20,30,50,10));

        snow = new CCParticleSnow(new CCPoint(490, 20));
        snow.Position = new CCPoint(490 / 2, 800 + 1);
        snow.StartColor = new CCColor4F(CCColor4B.White);
        snow.EndColor = new CCColor4F(CCColor4B.Red);
        snow.StartSize = 15f;
        snow.StartSizeVar = 2f;
        snow.EndSize = 8f;
        snow.EndSizeVar = 1f;
        snow.Speed = 5f;
        snow.Gravity = new CCPoint(0.5f, -2);
        snow.EmissionRate = 3.5f;
        snow.Life = 50f;

        layer.AddChild(snow);
        this.AddLayer(layer);
    }
}

Second one

public class SnowyBackground : ContentView
{
    SnowScene overallScene;

    public SnowyBackground()
    {
        var sharpView = new CocosSharpView
        {
            HorizontalOptions = LayoutOptions.FillAndExpand,
            VerticalOptions = LayoutOptions.FillAndExpand
        };

        sharpView.ViewCreated += (sender, e) =>
        {
            var ccGView = sender as CCGameView;

            if (ccGView != null)
            {
                ccGView.DesignResolution = new CCSizeI(490, 800);
                overallScene = new SnowScene(ccGView);
                ccGView.RunWithScene(overallScene);
            }
        };

        Content = sharpView;
    }

}

And in Xaml in Second page Now When I click an Item of listview in first page(page1) like below: Event handler for Listview item click in first page-

async void Handle_ItemSelected(object sender, Xamarin.Forms.SelectedItemChangedEventArgs e)
{
    try
    {
        await Navigation.PushModalAsync(new Page2(),false);
    }
    catch(Exception ex)
    { }
}

2nd page -

<?xml version="1.0" encoding="utf-8"?>
<ContentPage 
    xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
    xmlns:local="clr-namespace:Particle" 
    x:Class="Particle.ParticlePage">

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="*" />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>
    <local:SnowyBackgroundView HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" Grid.RowSpan="2" />

</Grid>

It navigates to page 2 and it successfully shows snow rendering. But when I repeat same steps... I mean If I click back button in page 2,then it goes to page1 and here when again I click lictview item,it goes to second page, but it doesnot show snow rendering, just a black screen.