Sharktooth Grill Question!!

Ok guys, I need some advise from you experts on the best way to repair my grill. It is in really good shape, except it has 2 hairline fractures about 2-3 inches long, one on the top lip, one on the bottom.

What is the best Glue/filler/adhesive I can use to glue the cracks together that will not split?
It was repaired once before,, looks like they used bondo,, but it cracked again so I'll need to sand the old stuff off 1st.

Please let me know,

THANKS!! :o