Need a little help with lengthening

My first novel is in its second draft stage, and I'm trying to make it longer without having to resort to pointless filler and such. Any suggestions you can give me would be greatly appreciated, and I will likely even give you a nice thank you in the book's credits. Beta readers would be very greatly appreciated as well. Thank you for reading this, and thank you in advance in the event that you should give me advice. I look forward to your responses, and have a nice day all of you. Also, any mods that happen to read this, please do relocate this if I've posted it in the wrong board since I wasn't exactly sure where to place this topic. (There should really be a "General" or "Other" advice board, methinks.) I do believe that covers everything I need to say, so now I am off to go look at more posts and topics and such.

Don't worry, this is the right board! (but I will bring up a potential other board c;)
What I generally try to do is think about things like episodes. I struggled a lot with lengthening stories without things being pointless, but all you really have to do is think about how the fillers add to the overall plot.
It would be much easier to help you if I knew more about the story!
How long is it? I have a critique trading hub and I've been looking for beta readers as well! I would totally be willing to trade critiques with you.

About 113 pages in MS word with about 14 chapters, and hoping to get it to at least 300. It's quite an uphill battle at the moment. At its core, it's about a king trying to protect his kingdom from various internal and external threats such as various types of undead, fascists, and other things. I also regret to say that I'm really not good at critiquing myself, so a trade of critiques would be... rather one-sided.

Okay, can I get a synopsis of characters n such? Let's see, you could always explore the threats individually if you haven't already. Have some run-ins, find places where they've been, have a character do some research on them or talk to somebody that's seen them. That could take up a bit of filler space. You could always use downtime scenes for developing character relationships, a little away from the main plot.

I sum all of them up quite effectively in my huge character topic! XP

On to the other points. Already explored the threats individually, iirc. second point, I've done a few things with that though researching a clandestine group of necromancers in medieval times isn't exactly easy. More downtime scenes may be possible. And also I just realized I have an unresolved sub-plot.