Your Immigration Expert
The likelihood of being granted a visa to enter the US from Canada for a Filipino on a tourist visa is limited at the best of times. The fact she has been previously refused will make that highly unlikely. I want to provide some positive news but due to my experience I would suggest you apply for a visa in Manilla and if that is rejected, for you to rethink your plans about texas.
As she is coming to be with her boyfriend there is a risk that she could look to stay in the US and is attempting to circumvent the immigration laws around prospective marriage visas, as these allow the US immigration authorities more opportunity to investigate your background and hers along with your earning potential to be able to afford to bring a wife into the country.
If your girlfriend is rejected on intention to return home and you have declared your relationship to the authorities, then the refusal of the visa on these grounds would support any future visa application on the basis of the relationship and her plans to remain in the USA with you. This would, however, mean getting married.
Girls joining partners from countries like your girlfriends have a hard time getting into several countries like Canada, UK, Australia and others as there is a high chance the relationship will fail based on government data. I am sure this is not the case in your situation, you have just fallen foul of the way immigration law views the world. The way the law works to keep apart like this infuriates me and I wish we could change it.
If you decide to get married if her visa is rejected please let me know and we will build a winning case on the grounds of the relationship if you are ready to take that next step in your life.