In order to be offered a period of retention, your Chain of Command needs to make a positive recommendation and be willing to employ you within their lines. I have worked with a broad swath of MOCs, and most of the time, when a CoC recommends a period of retention, D MIL C will grant that period.
I have yet to see someone get a new AR and have their PCAT changed to become a low risk of breaching the UoS. Even individuals who have come back and have no MELs other than requiring follow up with a specialist no more often than 1 year, have not been granted a second MEL/AR because they are 04 or G4 and greater. This all has do to with the medical risk matrix and the potential for a member to have an acute episode while deployed, and the medical intervention required to bring the episode under control.
For example, I had an individual who had suffered a heart attack. He recovered, made positive lifestyle changes, returned to full duties and could complete the PT test. But, because of the type of heart attack, there was an increased risk (greater than 50%) that he could have a reoccurrence that would likely be fatal in a deployed setting. He became an G4 05, and was given a medical release. We retained him for the maximum three years, but couldn't convince DMEDPOL to change his category.
Another example was a member with a history of kidney stones. They could not pinpoint the cause, so they kept reoccurring randomly. Other than when experiencing an episode, the member had no MELs that limited her from performing her duties. But, once again, because of the risk matrix, she was assigned a G4 04 which breached UofS, and was medically released.
All that to say, you need to be prepared that even though you are getting better, and could return to full duties (depending on MOC and how they aggravate your medical condition), a period of retention may be the best you get.