The texture is repeated (when repeat is active) infinitely in all directions and the co-ordinates for the texture can be the original or any of those repeats. They don't all have to be in the same area either so they can cross a repeat.
Basically, to repeat an entire texture 3 times on a square, start from (0, 0) and cover the area up to (the opposite corner should be at) the texture size multiplied by 3.
For any vertex in an array, to repeat 3 times within any shape, multiply the texture co-ordinate (texCoords) by 3. Similar for any number of repeats and each dimension can be repeated differently.