If I understand your post correctly you have already loaded a new version of IOS on your 1721 and have deleted the old image. This should mean that there is a single image in flash. In that case the 1721 will boot from the single image in flash. You can verify this in the output of show flash. There might be some other files in flash but I believe that there would be a single image file.
You might also want to check in the configuration of the 1721 to see if there are any boot system commands in the configuration. If there are any boot system commands you would want to update the boot system commands to point at the new image file that you have loaded.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.