I guess you can, since SoFi has no origination fees, but I didn't actually get the loan materials for the fine print.
I would say that provided your new refi company will refinance a private loan (which yours became once SoFi paid off the government), and has no origination or early termination etc fees, you probably could do this for the cost of the hit to your credit.
However, I'd be surprized if there were no language in there preventing you from jumping ship like that within x months, and/or that the new lender would refi an identical rate from a months-old loan. Credit card churning is probably a more lucrative use of your credit score.