Amberlyst 15 is a macroporous strong cation exchange resin. It can be used as an ion exchanger. It also can be used as a catalyst. If you use it as a catalyst, usually you don't regenerate. If you use it as a cation exchanger, it is usually regenerate with 2-4 BV (the resin's volume) of 3-7% HCl. To get a better regeneration rate, you need to put the resin into a column, the height of the column better not less then 500mm. Pass the regenerant from top to bottom in 1-2 hours. Then rinse it with DI water to neutral.

Thank you very much for your tip sir.

Best regards

Luca