At this point, I don't expect us to do much of anything, but here's what I do. It's not perfect, but it's best to be as prepared as possible.
First, and I would say that this is the most important, I would increase our ballistic missile defense. This war will turn nuclear eventually. Maybe not until the final stages of it, but sooner or later, both sides will be firing everything they have. Build it up as much as possible.
Second, I'd restart the F-22 program until we had at least 500 of them. In the opening stages of the attack, our aircraft will be heavily outnumbered and those are the best ones we've got. In addition, accelerate both the F-35 program and the Next Generation Bomber program. We're going to need as many as we can get our hands on.
Third, continue building the Virginia Class Submarines, hopefully at a rate of at least three a year. Restarting the Seawolf Class wouldn't hurt, either.
Fourth, keep all ten of the Nimitz class carriers until at least four of the Ford Class ones are built. Building more construction sites to help accelerate the buildup would also be wise.
Fifth, do whatever possible to increase our manpower. It's one of our biggest weaknesses at the moment, which we didn't really realize until Iraq and Afghanistan.
I've got more in mind when it comes to building up our forces, but it would at least be a good start. The less ground China gains before we can fully transition to a war-time economy, the better.