If you try all the fixes listed above and it still leaks, then it may be time to buy a new kayak with a warranty, and sell your kayak to someone you don't like for cheap.
Did Dan90210 tell you to say this?
But, yes, at some point with all the testing trying to find the leak, you are probably weakening the leak point(s) with all the testing stress. You may also reach a point where you can't fit any more pool noodles in the hull and the amount of time you are bilging becomes cumbersome.
I keep my kayaks for spare parts and for when friends want to go instead of selling them.
You should inform any potential buyer of a significant leak, if you do choose to sell.
