If you don't want to re-configure your Kernel from scratch, download and unpack the latest source tarball (ie from http://kernel.org/), copy the .config file from the old kernel to the new kernel directory, and run make oldconfig. Then run make menuconfig to change any options for the new kernel.

To update the symlink:

ls -l /usr/src/linux
rm /usr/src/linux
cd /usr/src
ln -s linux-version linux

DebianLinux users will want to read KernelPackageNotes for information on using make-kpkg(1) to build a Kernel Deb. If not, they can follow the same steps, using

apt-cache search kernel-source # to find out the latest version
apt-get kernel-source-version

to download the latest source.