some thoughts

Questions for yourself -

* Are you interested in figuring out a new approach? Is it helpful to your career? Is it in line with your career goal?

If yes, this is the perfect oppotunity to learn.  With the urgency of solving problem for the company, you might be able to get training etc. , to gain knowledge and experience. 

You would send email to director or schedule a one on one meeting, have an agenda with you, listing clearly what is the need (project needs to be done, with whole new approach), where are thing now (Peter gone, no one has done the new approach),  how to get there ( you are willing to learn, here is how - conferences, training, books etc), time line

If no, be quiet and look for a job.