Firstly, for your kind information, Blogger.com always taking your blog backup and that should be hourly basis and you will never loss your value-able contents. So, don't be tensed.
But a bit tricks for you and sharing with you one site. BlogBackupOnline really superb one site for blogger.com. This site will help you to take PDF, Techrigy's BlogBackupOnline allows users to create a full blog backup, schedule automatic daily backups, and restore or export a blog. 50 MB space you get free of cost and backups can be scheduled and restored can be incremental. This service can be used to import blogs, restore single posts, export blogs from one platform into another among other features. Supported platforms include Blogger, WordPress, Friendster, LiveJournal, TypePad, Serendipity, Windows Live Spaces, Movable Type, Typepad, Vox and Multiply and updating more features.
I think you like it and quite easier to use and secured too. Nothing needed. Just signup and enjoy !