I get the impession that you have never actually met this girl and if so, sending money is not a good idea. Besides, P15,000 is much more than the average wage in Phils, no wonder it looks like shes not interested in finding a job, as shes got no chance of finding one that pays as much as just being your gf.
I definately wouldn't consider sending more money to start an annulment process before you go there. If she is as nice as you believe and she is not scamming you, when you eventually go there to meet her, then you can accompany her to the lawyers office and find out how much money needs to be paid and when.
The annulment process is a long and expensive one with several payment stages and in my experience, if you pay too much up front to a lawyer, he'll just sit on it till you become impatient and then ask for more money to get things moving again.
Iain.