Ideally, neither. Do the work related stuff, but also man up and own up to the fact that you expressed romantic interest and it was not reciprocated.
Just treat it like it wasn't a big deal.
Or, if you feel anxious/awkward/nervous/sad/hurt/rejected, as would be a totally normal thing, then try to feel those feelings and own up to them and let it spill through into your expressions outwardly. People think thats lame, but expressing a hint of sadness when you're genuinely sad is also known as being authentic. Expressing a hint of nervousness when you're genuinely nervous is also called being authentic.
Any of these two solutions is better than pretending to put on some kind of front, which takes you farther away from relating honestly to her and to yourself. Nobody cares about your "cool guy" impressions, life is about being real with each other, not being fearless fake supermen. That's just my 200 dollars.