No and yes. But I solved the problem. Since my supply is going to be above 5V (which is always regulated through the 5V LDO) i will get 5V on PIC. But when my supply drops under 5V and keeps droping as the battery supply runs out, i need stable refernece on PIC's Vref pin.

I've done this with LM336-2.5V reference diode.

So all the time I know that the reference is 2.5V even if the supply voltage changes. Now i can do an A/D to measure the supply voltage.