"Ask it again."
你 is used to specify the target. However, you can exclude 你 to make the alternate sentence, which is also correct.
to Leillia and commentators: I omitted 你 and it still was incorrect (Oct 2018)
I put 问一次 which I thought I had put before and got it correct, which makes sense because "问一次" seems like it would be a proper command for someone.
Well, literally that means "ask one time" I don't know if that implies again but I doubt it.
Several times, the input interface on both the web and the android app seem to "retype" what I have typed, and always take the suggestions I have overriden. So if I select the second, "zai", in the list, when it get's "redrawn" I see the chinese selection pop up again when I hit submit, and the first option is chosen, as it is assuming that the input method uses the most recent selection. Why is it "retyping" what I typed, and thus changing my answer and marking it wrong? (I wouldn't think that if the Chinese selection stuff wasn't popping up again after I hit submit.)