Can't see any reason to replace it. Juat take it off and throw it away. It is only there as a legal requirement at the point at which the product enters the market - that is when the dealer sells the boat new. The "real" CE evidence is the Declaration of Conformity which is bound into the boat's handbook.
in practice, omce the boat is in use most that labelling becomes irrelevant as the first time you add or change anything significant on the boat it potentially no longer complies with the standard, even if the bits you have are individually certified. There is no legal obligation to keep a boat in the same state as the oroginal, nor does it have to be recertified following the changes.