SQLite loses data (insert, update) after restarting app

When I update my data:

using (SQLiteConnection conn = new SQLiteConnection(DB_PATH))
            {
                var query = conn.Table<kursy>().Where(k => k.kurs == kursStaryRubel).SingleOrDefault();
                query.data = kursAktualnyData;
                query.kurs = kursAktualnyRubel;

                conn.Update(query);
            }

Everything works fine. The data is updated. But when I close and open my application again, this data has old value - it's not updated. Why is it happening? I'm using the same database, it is not recreated.