Hi there :-)
I think the use of 'bots' is a sort of happy slightly childish and familiar extension to the word 'thrill', and meant to accentuate that word'. The idea is similar, but not quite the same as when someone calls someone 'babykins'. This would only be said between two people who are extremely familiar with each other and is a term of endearment. 'Bots' is similar but it's modifying the word 'thrill'.
A bit difficult to describe but I hope it gives you the idea.
Regards