search file (C-x C-f), repeat search history (M-r)

[michael]

Hi,

if I type

C-x C-f

and

M-r string

i can search files I previously opened, which pathname contains
string.

How can I match the next item in history which contains string?

M-r string

does that but that's too complicated, I just want do press M-r again
without a search pattern? Ok, I kann press M-r  UP but that's also too
complicated.

Any ideas?

Thanks
michael