One thing I do is archive games I finish that I plan to replay later. (current example being Dusk, as I'm working on my 3rd playthrough) and it gets annoying to delete all the time entries one by one, especially with how I am where I usually play for around 15 minutes a session. Is it possible to get a button that deletes all time entries at once?

I like this idea!

Just out of curiosity, what is the reason for re-using a playthrough when you replay a game? Do you have goals you want to re-use or something?

yup, I usually list all levels or quests in the game, and usually don't want to re-enter them, especially if I have to look them up. RPGs would especially be a problem with that

Another example I thought of is for why someone would use this feature, if someone starts a playthrough over after having a lot of time entries. (say they didn't like how they built their character or something and there's no way to respec)

I can definitely add a button to delete all time entries. Personally, I like keeping my old playthroughs (even if I didn't complete the game) just as a way to view my history (and eventually, it could lead to some interesting reporting options). But I'm all for making things easier for those that choose to reuse for whatever reason.

All that being said, I think the bigger issue is I need to finish working on goal templates

thats a good idea too x'D but if anything, this can solve this issue until then

Myself I archive games I finish and plan to replay at some point, or games I finished but want to complete later