1)In your resource file the usage of the * char is possible, at least in .NET4.0. So you should have no problem in setting the value in your resource file.
2)To append other value in ASPX file is not possible, but you could init your label in the Page_Load() event like in the next code:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
_lblName.Text = Resources.Registration.YourFullName + "*";
}
}