There are quite a number of salvage options now which didn't exist a few years ago. This depends heavily on the type/grade and position of cancer in the prostate, and your own attitude to risk. I don't know where you're being treated, but this is quite a specialist area and I would suggest getting referred to somewhere which does most of the treatments, such as UCLH, so they can suggest all which are appropriate for your case with their pros and cons.
Some more recent options are the focal therapies if the recurrence is focal, including in this case focal brachytherapy. Salvage radiotherapy after failed radical radiotherapy is also something considered nowadays providing there's been a reasonable time since the radical radiotherapy.
If you do go with salvage prostatectomy, many hospitals (certainly in the south) will recommend referral to a particular specialist surgeon in salvage prostatectomy at Guy's and St.Thomas's.