If A/C doesnt have a leak, how else would the system lose pressure after a recharge?

What is your question?

My A/C system has been getting warm so it was evacuating and then recharged. It held vacuum overnight and when we returned to it, the gauges were still exactly where we left them. So this means there pretty much is no leak. We recharged the system and added UV dye as well. All vents blow 40 degrees then 3 days later the A/C is warm again. First it slowly gets warmer on the passenger vents around 60-65 degrees and the driver side would stay 40-45 degrees. Then the passenger side would be up in the 70-80 range and the driver side has slowly crept into the 50-60 range now. If we turn the fan to medium to high settings the a/c temperature is warmer than when we leave the fan on the lowest/slowest setting. There is no sign of UV dye leak. When we had the A/C & fan on lo we checked the temp in the vent. It would fluctuate +/- 3 degrees. I just checked the pressures and I was getting 20 PSI on low side and 150 on high side. 3 days after recharging with 35 on low & 225 on high.

How long has your 2012 Lexus IS250 had this problem?

A month.