It depends if she really needs it, and how much money you can afford to give her without putting yourself in financial jeopardy.
In tough economic times or when faced with unexpected emergencies, your Lao girlfriend may truly need your financial assistance. If you really love her, and you have nothing to doubt that she loves you back then it's fine to send her some money.
Before you send any money, be sure to talk everything through with each other so the both of you know exactly what the money is going towards. If it's for general living expenses then you don't want to give her too much, and too little at the same time. A gift of $100 or $200 US each month is reasonable and will help her get by in Laos without you there.
Think about it this way, if she lived with you now you would be spending more than that on entertainment, dinner and gifts. Honestly in this day and age in society you need to spend some money to have a Lao girlfriend or any girlfriend for that matter. It's pathetic, I know, but that's just the way it is with most girls.
We all have a sudden overwhelming expense from time to time and as a result you will not have any spare money left over. Always remember there are meaningful, effective, and creative ways to help her. If she is working and earning extra income for herself then it would make things alot better and puts abit of pressure off you.