Ubuntu – Aptitude ugrade does not change the kernel

Sorry if the title is not very clear.
This is rather new to me.

I have ran this 10.04.4 LTS server for over a year now.
I have dutifully used aptitude update / aptitude upgrade on a regular basis then rebooted my server when advised to do so.

Today I was warned that /boot was running out of space. So I started looking into the removal of old kernels.

$uname -r  
2.6.32-38-server  

Then I looked at /boot and found that I had more recent versions of the kernel

-rw-r--r-- 1 root root 8547102 Dec 22  2011 /boot/initrd.img-2.6.32-37-server  
-rw-r--r-- 1 root root 8535914 Jan 25  2012 /boot/initrd.img-2.6.32-38-server  
-rw-r--r-- 1 root root 8539717 Mar 20  2012 /boot/initrd.img-2.6.32-39-server  
-rw-r--r-- 1 root root 8538788 Apr 10  2012 /boot/initrd.img-2.6.32-40-server  
-rw-r--r-- 1 root root 8538887 Aug 11  2012 /boot/initrd.img-2.6.32-41-server  
-rw-r--r-- 1 root root 8546431 Oct  5  2012 /boot/initrd.img-2.6.32-42-server  
-rw-r--r-- 1 root root 8545858 Oct  5  2012 /boot/initrd.img-2.6.32-43-server  
-rw-r--r-- 1 root root 8545789 Oct 14  2012 /boot/initrd.img-2.6.32-44-server  
-rw-r--r-- 1 root root 8547103 Feb 24 11:25 /boot/initrd.img-2.6.32-45-server  
-rw-r--r-- 1 root root 8546521 Apr 19 06:55 /boot/initrd.img-2.6.32-46-server  
-rw-r--r-- 1 root root 8545660 May 15 06:41 /boot/initrd.img-2.6.32-47-server  

This is confirmed by dpkg

$ dpkg -l | grep linux-image  
ii  linux-image-2.6.32-37-server     2.6.32-37.81                      Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-38-server     2.6.32-38.83                      Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-39-server     2.6.32-39.86                      Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-40-server     2.6.32-40.87                      Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-41-server     2.6.32-41.94                      Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-42-server     2.6.32-42.96                      Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-43-server     2.6.32-43.97                      Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-44-server     2.6.32-44.98                      Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-45-server     2.6.32-45.104                     Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-46-server     2.6.32-46.108                     Linux kernel image for version 2.6.32 on x86  
ii  linux-image-2.6.32-47-server     2.6.32-47.109                     Linux kernel image for version 2.6.32 on x86  
ii  linux-image-server               2.6.32.47.54                      Linux kernel image on Server Equipment.  

/boot/grub/grub.cfg has only one entry (menu?)

### BEGIN /etc/grub.d/10_linux ###  
    menuentry 'Ubuntu, with Linux 2.6.32-38-server' --class ubuntu --class gnu-linux --class gnu --class os {  
    recordfail  
    insmod ext2  
    set root='(hd0,1)'  
    search --no-floppy --fs-uuid --set f2ed5eb3-d3e5-4cc2-b45d-7190337be222  
    linux   /vmlinuz-2.6.32-38-server root=UUID=1cdc82de-7361-47f3-aeda-21b6929ef256 ro   quiet splash  
    initrd  /initrd.img-2.6.32-38-server  
}  

I'd like your advice on how I can get 'aptitude upgrade' to update grub.
I could also use some pointers as to how to cleanup some of this mess.

I found some posts that each seems to solve a piece of the puzzle. I'm a bit reluctant to try anything as my server is headless and remote (colo).