Probably..I encountered a similar problem last summer. You can pretty much go two routes, replace the whole assembly with a Progressive assembly, or just replace the spring with a Baron's spring, A progressive one from a certain v-star 1100 dealer, or replace it with a road star spring.
All the springs have a higher weight rating than the factory 1100 spring. If you replace just the spring, you'll notice a difference, but it's considered just a "band aid".
If you buy the Progressive shock assembly, you'll be spending roughly 5-6 times more, but it will be a huge improvement (from what I've heard).
I replaced mine with a Baron's spring and noticed a big difference, but you can still tell the shock is worn. But hey, for 50 dollars versus 400+, can't complain.
2013 H-D FXS Blackline
2006 V-Star 1100 Classic
1980 XS650 Bob (in progress)
USMC - 0331 - OEF