Advice needed: Wifi repeater for 3 storey housing

Hi guys, can anyone recommend me a good wifi repeater that can boost signal up to 3rd storey.

My current setup is this.

First floor : Starhub router
Second floor : repeater
Third floor: lousy signals

Seems that lately the repeater signal is getting weak. Not sure what's the reason. Time to get something stronger maybe. :)

Please advise. Thanks !!!