you could do 'rpm -e <packagename>' to remove the package first.
A better solution is to figure out what changed/what the problem is and fix it. Need more info.
What are you trying to accomplish? Do old apps that used to work (and haven't changed) NOT work anymore? Or are you writing code now that doesn't work? Maybe you 'all of a sudden' had a brain*&$! and that's where the problem is.
Just a suggestion.