i prefer to keep sparks for something else, like chapters.
Don't have an auto-dia addon but you can configure gearswap(this uses Mote library, you can find sample file around) to recast dia after each use:
Code
function job_aftercast(spell)
if spell.english == 'Dia' then
send_command('@wait 2;input /ma Dia <t>')
end
end
This will cast a new dia after the previous one (adjust the wait if 2 is not fast enough, depends on your FC). Just rest at any point and you'll break the chain. Remove it once done and boom capped skill :D
I also think spending spaks on chapter is not ideal as it's expensive, you are losing money over NPCins Acheron Shields and you are losing the opportunity to make/play with friends and get better doing HTBF for chapters.