metal flashing under weatherboards

[claire_t]

Hi!  I'm needing to replace some rotting weatherboards prior to painting, and have what I believe is some type of metal flashing between the bottom weatherboard and the skirt. The flashing is pretty warped in most cases and seems like it might actually be catching water where it's turned up- what's the best solution cost effective solution moving forward? Do I need to replace the flashing all around the house/ is it needed? Thanks in advance!