Correct pump sizing / pump replacement

Hi all -

I purchased a home 4 years ago with an inground, 40,000 gallon pool. This winter, my Hayward Super Pump (C48K2N143; SP-1607-Z1-M) died. Its rated at 1 hp. Is there a less expensive replacement pump?
Other specs:
1.5 inch lines; 3.14 sqft Hayward sand filter.

I am told that my system is undersized, but I'm not in a position to do a filter and service line upgrade. Can I replace with a 1.5 hp pump?

Thanks!