I don't understand you are selling Bitcoin and buying Bitcoin again.?? I don't have a good idea about this but if you want you can buy Bitcoin by selling your other currency Altcoin but I am not sure if you are going to sell Bitcoin and buy that Bitcoin again is it true.
Buying back Bitcoin or any other crypto isn't a new thing. Investors do it all the time, through DCA or one time buy. The only issue that may come up is not knowing when to buy back and be profitable. Sometimes one might sell off but can't find a suitable level to buy back. Price would've gone pass the level they sold. That surely hurts. It takes someone who is deep in Technical Analysis (TA) to be able to get a near perfect entry. I said near perfect entry because we don't get to know what level is best to enter the market except on hindsight. Since you said you didn't have "a good idea" about it, it's best to stay off it for your own peace of mind.