Are you still a named driver? If so and armed with the policy number you can call the insurer, explain the situation and they may issue a policy in your name enjoying the same or at least a worthwhile discount. Much depends on whether you were just on it for occasional use or whether whilst she was the main driver you were fairly close behind in frequency . . .
The other thing that I have seen done recently in similar circumstances was the quick taking of the 'Pass Plus' course (sort of advanced driving instruction) and the immediate offer of four years NCB by Churchill for having done so. For a driver under 30 that can work out a big saving!
A third thing that often works is if you do any driving as part of a job insurers will often offer two or three years NCD if you have several years on a businesses policy without accident or claim involving negligence or fault on your part.
Failing any of those you can always try just outlining the situation to a sympathtic broker who may negotiate a decent introductory bonus with a company she or he has a good relationship with!
Good luck! Funforus