It depends on the ohm rating of the factory tweets also the frequency points of said tweets. Usually it's best just to run a new set of components but you can check parts express for an option if you just need to replace the tweets. What car ? And what's the issue ?
Its a vaxuhall astra (UK) nothing wrong with them just got subs so wanted better sound from the front, only thing is finding tweetera thats fit directly into the OEM tweeters