OK, since the filter is fairly large and can handle high flow rates, the spa will set the requirements for your pump. Are you happy with the jet action? Too hard, too soft, etc. If you are ok with it then you need to target a pump with the same braking HP of what you have which is 1.5 BHP (1.5 * 1.0).

Todays high efficiency pumps have pretty high service factors so you may only need a 1 HP (labeled) full rate pump to match what you currently have. For example, my 1 HP Northstar pump has a service factor of 1.85 which is 1.85 braking HP. This pump would be more than enough for your setup. One thing to do is to compare the pump head curves, if you have one for your current pump.

As Carl suggested, a 2 speed version would be the way to go so that you have high speed for the spa and low speed for general circulation. Sta-Rite, Pentair, Hayward all make fine high efficiency two speed pumps. The Pentair Intelliflow is another option for multiple speeds but you will pay for that feature.