Replace or Maintain
Welcome to Bike Forums.
I spent 2020 riding around on a 2011 bike. Did 2,000 miles on it.
Assuming your bike is not giving you terminal troubles, continue riding it.
If you've a hankering to spend some money in the bike dept..... Then some tools to assist with it's maintenance and upkeep would be a good place to start.
You might also learn some new skills along the way.
Drivetrain maintenance is a good place to start.
Chains stretch with age. A chain wear tool will allow you to determine if the chain has stretched past the usable limits.
Dricetrains also require a good cleaning.
The tool to remove the Cassette from the wheel (for cleaning) and a Torque wrench in order to replace the cassette correctly are good options.
You'll also want to remove the chain for cleaning.
Maybe your chain has a master link (quick disconnect), you'll need master link pliers.
Maybe you chain doesn't have a master link, you'll need a chain break tool.
If you do have to "break" the chain to remove it. Do consider using a master link for reassembly, makes things much easier.
Just some ideas. After all, if you were to purchase a new bike, the tools to maintain it are still required.
I couldn't imagine having to take my bike to a mechanic every time my chain needed a cleaning.
All the best
Barry