Hi heres the thing, i want my extender/ old router to be in my room and the main router where it is, but in my room is it possible to have the old router/ extender without an ethernet cable, as all i want to do is have a wireless range extender without it wired connected to my new router
Pretty much any router can be used as a AP but to use it as a repeater it must contain the software to do it. The manual does not indicate it can run as a repeater. You only hope would be if you could find third party firmware like tomato or dd-wrt. I didn't find this one on the dd-wrt list of supported but that list is tough to read.
Question would be why would you put in your room. If you get good enough signal then a repeater will just make it worse in a many ways. If you do not get good enough signal the repeater will not work. It must have a clear signal to receive and then resend In general you want to put it half way between the router and the area you are trying to improve the signal.
I think bill has covered this off pretty well. Wireless Repeating can work well at times, but be sketchy at other times. Potentially you can actually degrade your primary AP wireless coverage, even though you are extending it in some other areas.
I know you don't want to run an Ethernet cable between the AP's. Maybe it's because the cable run is impractical?
Have you considered using Powerline adapters between AP's instead? This should maintain good/stable connectivity between the AP's without degradation of service. Just make sure the AP's are on different non-overlapping channels (1, 6, 11 on 2.4GHz for example).