My son (who is also addicted to this game) and I were lamenting how we rarely visit our oldest stores and have no real reason to revisit them once they are set up and running successfully. In the real world stores and businesses often do refresh/renovation/redecorations to revitalize the store and keep patrons coming back. Fixtures (like tables and chairs) get old and broken, carpet gets worn out, paint ages and bleaches out: everything just starts to look old and tired.
Maybe you could introduce a decay feature based on the time of a store’s existence (say 4-5 years). Once that time was hit for any given location, you would get some kind of notice that business is declining in that location due to old age and it’s time for a re-do. The player would need to take action to keep the business afloat by filling a meter, basically. To do so, they would need to utilize a combination of replacing fixtures, changing up the floor plan, and redecorating. Once they’d made enough changes to fill the meter, business would return to normal. Neglecting to change things up would see business decline to near zero as customers would gravitate towards the newer, shinier businesses in the neighborhood offering the same products.
This would give players reason to revisit their old properties and give them more things to do in the late game, as well as being a better reflection of the realities of owning and operating successful businesses.
I understand some players would be resistant to this as they’d spent a lot of time perfecting the decor the first time around. Perhaps giving an option to “Refresh” rather than redecorate. Refresh would come at a higher cost, but would basically be ‘pay this amount to keep things the same’ which would functionally mean repaint, replace worn out furniture and fixtures, and keep the same floor plan but without actually changing anything looks-wise. I definitely have a couple of my businesses where I’d likely choose the ‘Refresh’ option, but I’d welcome the kick in the butt to get into the others and mix up the decor.