As far as spring piston guns go, not really much lighter unless you get something with much less power. The less powerful guns have smaller actions, thus being lighter. Such as a Weihrauch HW30s. Just consider what you use the gun for and decide if you can get by with less power.
The cheap plastic stocked department store stuff can be lighter, but you will be taking a huge dive in quality from what you have now.
One big question is, what kind of scope are you running? A high power scope, particularly the more affordable ones, tend to be very heavy. A heavy scope can really make a rifle feel unwieldy and bulky, and swapping to a lower powered much lighter one can make a big difference in feel. I've found that I can get away with a lot less magnification than I thought I needed.
The pump guns are very light and compact. But also very loud, and most have terrible triggers and problems mounting a scope solidly.
Going to PCP would allow you to have a lightweight and high powered gun, and also quiet, but they are a big investment to get started in having to include the fill setup.