about 3 months, there has been a lot of fluctuation causing the price of ETH to drop dramatically. At this time Should hold ETH ? Can ETH price increase again 1k3$ again in late 2018 ? 
There's always a possibility in cryptocurrency industry and every coin prices is unpredictable and if you have an investment in ethereum that's the one thing you want the most and right now the value of ethereum is lower than $400 so the best thing to do is to hold it and wait for it's price to rise.