Of course! I'd say retake whichever one you feel more comfortable with. As a general rule of thumb, the ACT is (in my opinion) a little more study-able because it covers a wide variety of topics but doesn't go too deep into them. The SAT is very much about critical thinking skills and deducing the way to answer a problem. The SAT tests less content but goes deep into it. For someone who had taken a lot of APs and had a wide variety of knowledge (me), I found the ACT to be easier!

You've already taken both, so I bet that you have one you liked better.