There is, but I did the same as you and had to use the coin to get more fishes. On returning to the top of the tower, and feeding the cat I tried to descend. Much to my dismay, you can't climb back down the tower. I also had no more coins.
Ttssattsr,
Tue 1 Jul 2008, 17:23,
archived)
You can. You can jump off the edge of the force-fieldy levels.
Kamikaze Stoat £4.09,
Tue 1 Jul 2008, 17:28,
archived)