For what I understand of your problem, I'd use find along with cp.
something like
Code:
$ find . -ctime -7 -exec cp {} /path/to/destiny \;
This should copy files with data modified in the last 7 days (you can specify minutes instead of days with -cmin n, and you can use access time instead with -atime. You can compare with an existing file with -cnewer <file>).
I'd recomemend you to read
man find.
Also, I'm pretty sure there are several other ways of doing this.