Hand wavy economics. I love it.
The fact is,people, that economics is not a science. Unlike the (more) axiomatic world of physics and math,economic principals hold true much less in the real world. Yet for some reason, people think that they can formulate theories about how economies work in certain situations. This is tantamount to trying to predict which way the wind will blow.
Don't be ridiculous. The surplus can be invested overseas to buy up foreign competitors and suck away the profits, creating even more trade surplus. The surplus can be invested in creating higher margin export industries domestically, again growing the surplus.