Thanks to all who replied to my original question.

I tried all the commands like "make reinstall", but none of them did the
trick too well.  I guess these commands work well for a simple package
which doesn't depend on other packages (that haven't been installed yet).

"make reinstall" installs only one particular package, not the ones the
package depends on (at least, that's what it did for me, when installing
kde).

> > Okay.  But kde (for example) depends on several other packages (I don't
> > even know which ones).  How do I "make clean" all of them?  Hm.  I guess
> > I just "make clean" in ../pkgsrc ?
>  
> "make clean-depends" will do a "make clean" in each of the dependency
> packages.

This might be a good way, then.  I ended up doing "make clean" for the
whole pkg tree and after this, "make install" in ../kde did everything
that was necessary.

Thanks for the replies again,

  -jm