What are the conditions for switching Tier 1 to Tier 4 again

[immune2u]

Hey guys!
I came here for my master degree study under Tier 4 (student visa) in 2011 feb and after finished i got Tier 1 (PSW visa) and i am still in Tier 1 which will be ended in 2014 august. before expired my Tier 1, I want to switch it back to Tier 4 again. I have already done master degree so if i do same level of degree again then is there any possibility of getting Tier 4 visa as UKBA website doesn't mention about it? Anyway I can remain here just for 5 years and if i do the 1 year master again that will be finished within 5 years. another thing I have checked in UKBA website where these kind of conditions are not mentioned. If i do PhD then that would be exempt of all these conditions. But again my confusion is:
If i do master degree again then will i be able to switch my Tier 1 to Tier 4 which i can finish within 5 years of mine being in UK?

Please guys I want to be clear in advance so I can make my further plan being sured so, help me out.

[madhumesh]

Currently If your Visa is Tier 1(PSW) you can switch to Tier 4 as per this.