Hi Charles,
If you do you should make sure that this is spelled out very clearly so someone who already owns it doesn't accidentally buy it thinking its something new. You should also probably run it by your retailers first to see if there are any policies in place for that.

someone who already owns it doesn't accidentally buy it thinking its something new ..

Maybe you can incorporate an additional set of characters to "soften the transition". That way, you can clearly point out functional differences -- perhaps it'll make owners of the "old" version buy the new name as well.

Back in the day Letraset released a font and they named it "Playboy". They then changed it to "Plaza" without much fanfare. I suppose Hugh and his crowd took exception.