"What are you up to now?" is ok, but it can imply that the person is "up to something" which in turn may imply that it is not good and then that person might get offended. People usually say, What's new? What are you doing now? How's things?

Lisa, What are you up to now? This is an informal expression that you would only use with friends. You would never inquire into someone's personal business in this way on a professional level. Think about what you are asking. You want to know what the person is occupied with at this very moment, either out of curiousity or because you would like them to do something else. It can have the simple meaning of "What are you doing now?" In that case the intonation pattern would be approximately: WHAT r u UP to NOW.? If you change the pattern: WHAT r u *UP TO NOW?...the question becomes even more personal, perhaps sarcastic, and might imply disapproval. Intonation is very important to native speakers.

If he is your freind you need not think of his being offence If he isnt your freind as usual you assk him professional

yes you can ask that person this Question for sure in fact this is correct. and no need to hesitate.

When someone is busy (genrrally with a bad work),we say: what are you up to now?