Review the reason for updating
Read the selected release's notes and compatibility details. Confirm that it targets the Minecraft version and loader you currently run. Record your current Clumps filename so you can identify the previous setup later.
Replace the file while stopped
Close the game or stop the server before changing jars. Back up the world and relevant configuration, then move the old Clumps jar out of the active mods folder. Copy the replacement into that folder without leaving two Clumps builds active together.
Check startup and a familiar task
Restart and save the log. Load a test world or a backed-up copy and repeat a known XP collection task. Keep unrelated updates separate until this check is complete. If a problem appears, stop the instance and restore the previous file, then compare the logs. Keep your backup and notes until you have tested enough normal play to accept the update.
Next step: read the installation guide or find a matching download.
Project reference: Official Clumps project and file details.