When do you retire your LIPO?

[rcs2022]

Have some Lipo's around a year and so old with some 40 to 60 cycles on them, the punch is not as much compared to a new one, moreover they are not charging to their full capacity anymore as i suspect the voltage drop is substantial and the LVC is kicking in before the rated mah are used up. and lastly they swell a bit and get hot to 50 - 53 deg C after some hard bashing.

Time to retire them? any other uses? am i compromising the ESC?
Is 50 cycles on average enough, or should i be getting more? I heard that cycles are in the hundreds before having the Lipo depleted.

I measured their internal Resistance using this formula:
IR of battery = V drop * R / (V drop + V no load)
Using a Extech EX 330, should be quite accurate.
Getting IR of 25 to 45 milli ohms per cell, checked my new Lipos that arrived got around 35 milli ohms ?! but they are quite punchy, i get to bash hard and use all the 5000 mah.

Should I be measuring the IR when they are fully charged at 4.2 v per cell or when they are used up?

I know these are a lot of questions but would appreciate some feed back, ideas, experience in this issue.