How bad is it leaking? While I agree that the "best" course of action is to tear the tank down and redo the silicone, if we're talking about a steady drip to small stream I'd just empty the tank, mak sure its dry and smear some more silicone in the leaking area.
I bought a 55 one time that dripped from 1 corner. I used about a nickle sized drop of silicone in the area of the leak and it held for years until I got rid of that tank.
If its leaking fast, then you're going to have to reseal it.