On the left side of the screen (under the "Normal" tab) there is a section called "Axis:". You can flip the X and/or Y axis there before exporting.
I must say that in 1.8 there is a bug that affects flipping in some way. Please see: https://github.com/azagaya/laigter/issues/31
To workarround it, modify "distance" slider AFTER checking the invert checkbox.