Then the answer is to do nothing. Otherwise, your plan may include something like, "keep some powder dry." Typically, if you get caught in a move like that the only way to recover from it is to have the ability to increase your size substantially. Although, it's clear to see that can create Bigger problems.
my 'plan' or 'system' was caught against the straight fall. I had a real big loss in ESI, and lost much of profits back in SYK. Now am flat for this week, and too much pissed to place another trade for the day. Worst week for me in the past six months; there were awful execution issues too.
Your question is not well focused. It depends on what you are trading. Not all stocks/futures/instruments went the same direction or even moved. The futures shot down this morning in a semi-relentless sell off. It didn't provide any setups that I saw. (Although there was a good sell signal about 10 minutes after the jobs report this morning. (Pre market open) The best thing to do is wait for a trade that looks good to you. If you're a trend trader then this morning may have been a good opportunity to take a short term trend trade. Your style/plan is everything. Trend, counter trend, time frame, etc. is all important.