The fact that you don't understand the basic concept of of this means your probably shouldn't be cycling. Not to mention, how on earth do you run out of gear without planning??? But enough of me giving you shit.
Yes you can swap it. But what you said makes no sense...you said the test ex is 250mg/2ml? I've never in my life seen that measurement. Everything is "per ML" (1ml). If that is the case, simply draw and inject 2ml and your right back where you started.