The closest rephrasing of 'what are you after', using the word 'do', would be: "what do you look for?" Similar meaning, but importantly there really needs to be some verb following "what do you..." Though as a stand-alone phrase I'd still use "what are you looking for?"

"What are you after" is a colloquial way of saying, 'what are you looking for'. For example, you go into the kitchen and start looking around, moving things, and your mom says to you, "what are you after," as in 'what are you looking for.' In regards to Yuriy's comment, that doesn't sound right to me either. If you're talking about future plans, it should be What will you do after [the event]? What will you do after you win the game? etc If you're trying to ask some what they normally do after work for instance, we'd usually add another word in there: What do you normally do after [work]? Yuriy's question would be acceptable if its in context, eg A: What do you do on Sundays? B: I go to Church. A: And what do you do after? (implying what do you normally do after church on Sundays) B: I go play sports.

I agree with Toffler. I think aside from the fact that "what do you after?" is an incomplete thought, it doesn't also equal the meaning of "what are you after?" thus, "what do you after?" must come with a verb after the pronoun 'you': "what do you do after.....?" "what do you get after...?" what do you see after....?" :)

Toffler is certainly right. And "what do you after?" is simply no English (and even when corrected would mean something entirely different). As a small addendum, "What are you after?" can also mean something like: "What do you hope to get out of this?" (which is like "What are you looking for?" but in a non-literal sense). It can also mean: "What is your goal?" To be "after" something is to 'chase' it as your goal, essentially. Eiter to obtain a literal item, like a knife in the kitchen, or doing so metaphorically, like seeking a goal. Examples: "I'm after the big prize." == I'm seeking to obtain the big prize. "He was after blood." = he was seeking revenge.

"What are you after?" is sometimes used instead of "what do you want?". It could be short for "What are you going after?". "What do you after?" is not a common English phrase. "What are you after?" is perhaps a "slang" expression, meaning that it does not really mean what is says word-for-word.