I would only change it if you want to. To me, it doesn't look that old-fashioned. When I think of old-fashioned, I think of mullets & big handlebar mustaches. Anyways, if you DO want to change though, simply growing it out a bit and going in every so often to have it trimmed up might help. Use a little styling gel/spray to get that polished look. Something like this: link
you could grow it out long and get it styled so it doesn't just look ragged. what I do is I grow mine out to be medium length than I get my girlfriend to layer it for me and it looks a billion times better.