Hi,
No offence, please, but you are playing an unfair game.  If you don't like your present girlfriend why do you stay with her ?  If you really want your ex g.f better leave your present g.f. and do your best to get back to your ex.  The easiest way is to ask her face-2-face (that's the best) but if you can't do it than you have 3 options: To send her a mail (snail mail or e-mail) phone her or send a person you trust to do find out for you. 
Best regards,