If I was bladder retraining a patient who had been unsuccessful in a trial without catheter (TWOC), providing that the patient was aware of full bladder sensations, I would consider the use of a catheter valve (usually attached to a leg bag). This would allow the bladder to fill, and then be emptied when necessary (and help to reduce damage from the catheter tip on the vault of the bladder). I suppose that it is comparable to catheter clamping, but a more up-to-date alternative, easier for the patient and prevent the clamp being applied to the actual catheter, and possibly causing catheter damage.
If the patient was not able to manage without a catheter, a catheter valve would usually be one option; however, I would also look at intermittent self catheterisation. It would depend on individual assessment.