In my worlds at this point, I would start a new world with either a new (more difficult) modpack or else the same modpack, but with self-imposed rules, such as no quarries.
Every world, I try to do things differently, whether it's a new set of mods, new rules, etc.,.
For example, I just finished a MagicFarm2 world where I fully explored Thaumcraft 4, Blood Magic, Bees and Trees (bred lots of species of bees and made some super-trees), and then installed BigReactors and made huge reactor then a Steam Turbine. I got bored after I had already built some big structures, nice-looking bee and tree farms, and had an MFR laser fully-powered for a week or so.
Then, for something *completely* different, I've been on a relatively new world for a week with the Learning GregTech mod-pack. At this point, I'm mostly learning
PFAA, but learning GT itself is also a learning curve. No TE3, no BC, no Forestry, no magic mods, just pretty much GT, RC, HQM, PFAA, and a handful of supporting mods.
In a previous world, I limited myself to food power only (ExUt Culinary Generator for power exclusively), no infinite water : just Forestry rain barrels, and no quarry, laser, etc.,. Just bees for resource production.
I've also played a few Ag Skies worlds and I have Crash Landing on my eventual to-do list.
But, that's just me. Everyone has different tastes. My point is to push yourself to do something different.
