how to raise front end of car?

Raising the car is not a issue,you simply adjust the torsion bar bolts to the height you need.The bigger issue is why its getting lower.Possible causes,torsion bar are getting very weak and need to be replaced.
Transmission cross member where torsion bars go into and attach are rusting out and metal is becoming weak causing the torsion bar to twist in the frame.Possible front end problem with front lower tables.
If no rust issues appear,replace the T/Bars with H/D units,readjust the height and re-aligin,mrmopartech