Sometimes is the best answer we can give for this. 

Our core lines such as our own label jeans, t-shirts, sweat pants etc, are regularly re-stocked throughout the year.

Many branded products such as Mish Mash or Mustang jeans are generally one-off productions, and won't be re-stocked. We only re-stock seasonal lines in time for the start of the season, such as jumpers at the start of winter, or shorts for the summer, but will normally repeat popular colours each year.