Sometimes persistent drainage is related to excessive activity that prevents the skin flap from adhering to the underlying abdominal wall tissues. Sometimes there may be contamination or sub-clinical infection of the drain itself, which can cause persistent drainage. Removal of the drain is sometimes all that is necessary in this situation, but as often as not, another drain will need to be reinserted.
If the drainage is clear and yellowish (not cloudy or foul-smelling), perhaps your surgeon will consider sclerotherapy, where tetracycline is dissolved in a small amount of saline and inserted into the drain tube with mild pressure (never forced). This causes irritation and inflammation that can aid the tissues in "sticking" down and allowing the drainage to diminish until appropriate for removal. Every surgeon uses a slightly different amount, but I generally feel that less than 25-30cc per 24 hours is the time to pull the drain. Of course, a check to see if you are retaining fluid after drain removal (sclerotherapy or not) is a good idea within 3-7 days.
If a pseudobursa is allowed to persist for too long, sometimes re-operation to remove the fluid pocket is necessary to allow things to completely heal. Quilting sutures can aid the healing process, both at the initial surgery, and at pseudobursectomy, if needed. Good luck!