Looking at scorecard, 'upvoting' isn't even on the list. What helps is good questions, good answers, and getting others involved (which good Q&A does, but you can also contact people you know directly and get them involved).
According to my reading of scorecard, what will help most is a little bit higher rate of questions (so send in more code to be reviewed), and a higher answer ratio (more people answering a given quesiton - so review code!). It appears to me that this site is already over the hump many other sites face of getting enough hits. It just needs a little bit more content creation.
Having said that, we do need more people upvoting. You need to reward good behavior - ie don't upvote everything. Upvote good questions and good answers. And comment on those that aren't 'good' so people know how to improve them (which will result in edits and then in upvotes). Upvotes get people reputation and it appears this site has alot of visitors but appears to have not as much participation (since not a lot of voting).