GDP is a measure designed to represent production. Resales are not new production.
As a practical matter, they do represent consumption spending. However, look at the formula:
GDP = household consumption plus net investments plus government spending plus net exports
When consumption spending is increased in this formula for these resale, the result is not an increase in GDP: the result is an equal decrease in net investments, since resales come out of inventories. Any profits from the resales would increase GDP, though, as value added.