Ok, the battles have been costly, some forces have cried 'no mas' and withdrawn from the sector. As the battles rage across the planets though supply lines do still exist and reinforcements have arrived to those who have called for them.
So, here is what you have folks. The amount of reinforcements available is tied to the performance of the factions thusfar. Each player may add an additional:
Xenos - 2,000 points
Imperials - 1,700 points
Chaos - 1,800 points
Additionally you may remove half that number from (rounding up) from your surviving points and swap those forces out as well. So, for example, if I have 13,000 points of surviving troops I (as an Imperial player) can add in 1,700 points of new forces as well as swapping out 850 points of forces for something that i need more than what is sitting on my list at present.