To the best of my understanding, medications for overactive bladder do not actually cure the problem, so you'll only notice the results as long as you actually stay on the pills. If you have overactive bladder, once you go off the pills it is most likely that your bladder will return to how it was before you started the medication.

Problems with urination are very common after treatment for prostate problems, and many doctors like to allow up to a year after treatment for healing to take place before attempting to treat incontinence, to see if it will resolve on its own. I'm not sure how long you've been on medication, but if you started less than a year post-treatment, you could consider going off the medication to see if the problem has fixed itself with time and healing.

Also keep in mind that medications only treat overactive bladder, which can cause one type of incontinence (urge incontinence). It doesn't treat stress urinary incontinence (if you leak urine when coughing, sneezing, laughing, etc.), and it doesn't fully treat mixed incontinence (when you have both urge incontinence and stress incontinence). Make sure that you've been tested for stress incontinence as well, and if you do have stress incontinence, you may want to look into the surgeries that are available to treat that.

Good luck!