Personally, I would buy more depending on my budget and HODL. There is no point of selling your bitcoin when it is at its lowest. It would not be profitable, depending on you investment. It will be the perfect time to buy for us. And expectedly, since most of us have rhe same mindset, bitcoin will rise up again.
It's just like any other currency, stock, or commodity: you want to buy into weakness and sell into strength. Of course, easier said than done. And always keep some cash around to take advantage of opportunities.