Loses wifi connection then won't reconnect again.

I have this problem with my old MBP (late 2008). It loses wifi connection when my network drops (of course), but it won't reconnect again automatically after my network resumes its connection.

I have to turn off my wifi manually on the menu bar then turn it on again, only then it will connect to my network again.

Here's my screenshot:

I couldn't find a fix for this problem. Anyone here experiencing the same? Thanks.