For now buy more and hold. Investing in bitcoins for the future of your kids is really a great idea and now that bitcoins price dropped more than 40%, I can say that it was a good time to buy and hold like you are savings in a bank. Bitcoin will surely be the future of your kids if you believe that it will increase more and make another record high. But always think more than twice before making some decision specially in this volatile world of bitcoin. Always be wise in investing!