In my opinion, it takes effort to develop one's own strategy. Even if you use a pre-made strategy, you should modify it slightly to make it unique to your needs and goals.
No you should not ignore the losses. Instead, you should constantly try different strategies and learn new things on a regular basis to assure your success.
Demo is intended for practising trade, we must not forget that we learn through practice. Through demo account, we learn about real account and through the knowledge gained on demo trading we make real money through live account.