You must report any money (or right to receive money in the future) that unexpectedly comes your way while in a Chapter 13 bankruptcy. Failure to report this newfound money can result in a dismissal of your case and, in certain circumstances, cause bankruptcy fraud charges to be brought against you, even years later.
The best thing to do is to contact your bankruptcy attorney and explain your situation.
Bankruptcy attorneys are very used to these types of things happening and will know exactly how to advise you in your particular and unique case. The advice you get may be better than you are expecting, such as potentially being able to get out of bankruptcy early, under certain circumstances.