[jhv48]

Some times the belt will leave black deposits on the pulley after slipping a few times. Other times, they will glaze up the pulley so it can't get a good bite on the belt. Rough up the pulley surface if you find the glazing.

Check the pulley for black deposits and try to scrape them off, if there. Also, check that there is no slight coolant leak that is occasionally dripping onto the belt.

Last resort.....replace the belt again!

Oh yeah, it won't hurt to rough up the belt too!