How to use Android in Wi-Fi repeater mode by bridging Wi-Fi with Access Point?
That's not worth the trouble.

It's not supported out of the box by Android and you would have to (re)compile and configure and script many things. The dedicated router is the more reasonable and stable solution (and it's also cheap).

Reasons are the following. You would need:  


USB host support
finding a USB wifi module that's supported by linux
Compile a kernel module or a new kernel (to support the USB module)
bridge utilities (maybe), bridge module in linux
a working wpa_supplicant binary for the new USB dongle
time
17EUR+ costs (Wifi USB dongle (starting around 12EUR) + USB OTG cable (5EUR))


In contrast to this the cheapest repeater-mode wifi router I found on Amazon was 18EUR and requires null additional fiddling (plus has a better antenna).