How to repair leaking middle joint of pool slide?

[lobes]

I have a pool slide that leaks from the middle joint. I put silicone caulk to prevent the leak last year but it started leaking again this year. There is a slight crack in the upper half of the pool slide where it meets the lower half. Can I caulk over the previous caulking or do I need to remove the old caulk 1st and recaulk? Is there a better way of stopping the leak?

How to stop pool slide leak? - Album on Imgur

 

[Bama Rambler]

I'd remove the silicone caulking and apply some polyurethane caulking to the joint. It should be more waterproof and will definitely stick better.