First of all, you need to make research about this ICO. Not all ICOs token price go down, but a huge part of them. If you know, that price will go down after ICO it`s cost to sell tokens immediately and after 5 days buy it cheaper.
I think we need to wait until it recovers again and this is what many people are doing today they are holding their coins to avoid any loses because most people believed that soon market will increase its market value.