Happy New Year.
I would try TCA precipitation or Lyophilization however, make sure you do this on a small amount of your protein first and check to see if your protein is functional etc and you get a good amount of protein back.
Also, there are many column kits for concentration/purifying proteins including small proteins such as yours.
You can even get rid of most of the larger contaminant proteins with a column that has a low cutoff, ie only keeps proteins of size 15kda or less.
Good luck and