You have made a profit in your investment already, so it is better you sell it for USDT first. Wanting to invest in another altcoin immediately after earning profits from your earlier investment is not advisable now. Other altcoins you want to invest in, do as much research about them to know their potential of giving you plenty profit in the long run just as this one has given you. If you think too much about the transaction fees to buy later, that would only make be at an higher risk if you’re not sure of the coins potential that you’re swapping to. Take your time to get as many confirmations before continuing with the choice that will give you good profit. The good part of the initial investment is that, your aim of investing to get profit has already been achieved, so take your time before making the next choice of investments because of the long time effects of altcoins of not trusting very well for a positive outcome after investment.