Seriously, there are some types of damage that I wouldn't try to fix. Leaks caused by seams failing, and punctures larger than pinholes are repairs that would make me nervous. I'm not an expert on BCD repair, and there may be ways to safely repair these types of damage, but I know that whenever we had a seam come apart on a Zeagle, they told us to send it back because the bladder would have to be replaced, and that one time I had to recover the bodies of a guy and his girlfriend, (not diving from my boat) and when I tried to inflate his bcd, air just poured out from a big blob of aquaseal on the shoulder. They were entangled and I believe that the bcd failure was the first in a series of problems that killed both of them.
I realize that the OP is talking about a very slow leak here, and my remarks aren't really directed at him or her as much as towards someone who is reading this, that might be contemplating repairing a serious hole in the bladder themselves.
That being said, I think it is definitely worthwhile to dunk it and look for the source of the leak, as others have suggested, because the vast majority of the leaks I've seen come from the salt in one of the dump valves, loosely assembled dump valves, a perforated corrugated hose, or a missing o-ring or gasket. Any of this stuff is easy to fix yourself.
I'm sorry for the viagra remark, which obviously is not a viable solution because of the drag that it would create.
