if you bought the coin even with CSPR/USDT pair for example you can automatically use the other pair, but if your money is in USDT for future buying of the asset you should trade it to the corresponding pair that you want first.
Is it simply to sell the coins and then buy back as BTC pairs?
I’m worried the buying and selling fees would add up to a lot. Is there any other way to achieve this?
if you use cex though, you can simlpy be the market maker then you will be saved from a lot of fee, not necessarily free though, but at least it will ease your burden of needing to pay some humongous fees.
remember, if youre still not yet buying the coin, like your money is in USDT, the only pair you can use is the USDT pair but if you already bought it, its basically allowing you to buy from various pairs, so definitely in this case you don't need to worry you can directly use the pair that you want since it seems you already bought the coin.