Backups are NOT the answer! If you are doing any kind of coding, you should use a revision control system, like SubVersion, GIT, or Mercurial. It will save SOOOOOO much heartache and pain.
Even for small personal projects, an RCS is essential. Full-featured IDEs (MS Visual Studio, NetBeans, etc.) have RCS interfaces built in. I could understand why Erel doesn't want the significant effort in supporting different RCSs in B4A, but even a standalone solution only takes seconds to commit or rollback changes.
What Graham says is true. One thing to do for a short term solution is to use something like dropbox and develop out of it directly. At least that way everything is always being backed up so if your PC dies or something happens it is all still there. Someone here gave me that pointer out a long time ago and has saved me.
Take a look at Carbonite (http://www.carbonite.com/). It does automatic backups to the cloud and, once set up, you can forget about it. Then you don't have to remember to do backups since it will do them continuously. It has saved me several times - not only after a complete disk failure but also several times in being able to recover an older version of a file inadvertently changed (or even deleted) since it keeps multiple versions of changing files. At $59.99 a year, it is cheap insurance against data loss.
If you don't want to go so far as a formal RCS or involve the cloud (some of us don't trust it), just do 'nightlies' - export as zip to a folder of daily zips. It literally takes just seconds and the most you will be out is one day's work. For extra safety, use external storage for your nightlies...