How to change the alias of a key within a keystore?

I signed my JWS application MemorizEasy with a key whose alias is:

memofile.reference.emma.jar=/Users/simpatico/.netbeans/6.8/modules/ext/emma.jar

I don't remember why I chose such a long alias. I suspect it was memo only, but in my project settings I have:

jnlp.signjar.alias=memofile.reference.emma.jar=/Users/simpatico/.netbeans/6.8/modules/ext/emma.jar

I'm now updating the application and using maven I need to specify the alias as:

<keystorealias>memofile.reference.emma.jar=/Users/simpatico/.netbeans/6.8/modules/ext/emma.jar
</keystorealias>

Yet that doesn't work. Trying another key with alias mjee it works.

So could I change the alias of the key? If so, how? Otherwise, why wouldn't Maven accept my alias?