1991 BMW 525i Transmission leak

I have a transmission leak that is worst in the winter than summer. Should I just have the transmission resealed or replaced/rebuilt. The transmission doest not slip if there is enough fluid in it. I understand that the transmission must be dropped to reseal it and at that point of time, a replacement should be considered. But the cost to replace may not be worth it. Also I was told that a rebuilt transmission will never be the same on the BMW.