I figured out a better way to get your new blog running and not lose your readers.
Step 1: Clone the blog with a new address
You can create a new blog with the address you desire. Then clone your blog to the new one. To clone, you can go to Blogger.com dashboard and (skip the first 2 steps if you haven't manually modified the template of your blog):
1. Download the template of the old blog on page Layout|Edit HTML;
2. Upload the template to your new blog on page Layout|Edit HTML;
3. Export your old blog on page Setting|Basic|Blog Tools;
4. Import the xml file to your new blog on page Setting|Basic|Blog Tools.
Step 2: Tell the readers your new address
You can add a description below the title of your blog to tell the readers that you have moved by editing the Header in Layout|Page Elements.
Step 3: Automatically redirect to your new address (optional)
To add the redirecting code, go to the page Layout|Edit HTML of your old blog. Look for the tag <head> and add these right below it:
Change old-url.blogspot.com and new-url.blogspot.com to your own URLs.
Look for tag <body> in the template and change it into:
Save the template. And it is done.
After this, whenever the users enter the Home of your blog or click on any labels, they will be redirected to the new blog.
That was how I changed my blog from ttt-jl.blogspot.com to tiptt.blogspot.com. Click on ttt-jl.blogspot.com and you can see how it will be forwarded.
Before this solution, I have tried to use Settings|Publishing|Custom Domain to forward the old URL to the new one. Unfortunately, Blogger.com doesn't allow me to forward to a blogspot.com address.
If you have any better ideas, please let me know.