Find next item using Linq based on the last Index : I want to search for a string in a list of strings and get its index

        List<string> list; 
        int index;
        private void button1_Click(object sender, EventArgs e)
        {           
            index = list.FindIndex(x => x.Contains(textBox1.Text));
            if (index >= 0)
            {
                listView1.Items[index].Selected = true;
            }
        }

Now if the user hits the button another time, the index should be the next occurrence of the search item in the list. How can I do this based on the last index `index`?