As the question title says, I was wondering if there is a good or accepted way of "bumping" old and unanswered questions to show up again on the questions list?
Yes, there is, and it's even in the faq --
What if I don’t get a good answer?
In order to get good answers, you have to put some effort into your question. Edit your question to provide status and progress updates. Document your own continued efforts to answer your question. This will naturally bump your question and get more people interested in it.
When you place a bounty on a question then this will also bump up the question (and in addition it will be featured in the bounty list).
But note that a bounty for unclear questions is not gonna work well. Attention is not the only thing that drives answers.