Alright, Chaz...new tricks?

[houlahoops]

So my dad's dog is in some serious need of mental stimulation (that is, I need to work his brain so he stops telepathically torturing the other dogs and stealing my armchair). But as a terrible trainer and not very creative person...I have no idea what else to teach him.

He's a really sharp little dog, and his current repertoire includes the following (excuse me if some of the translations are bad...I will explain where I can because I don't use English commands):

Sit: also, "sit pretty" in which he tries his best not to look like an empty beanbag
Heel: self-explanatory
Come: self-explanatory
Down: self-explanatory...I also tried to teach him to cross his front paws from this position but his chest is too wide
Roll over*: both ways
Play dead: also, "more dead" gets him to stick out his tongue
Spin*: both ways
Twirl*: spinning on his back legs
Bring ___: self-explanatory
Woof: self-explanatory
Hound dog: phrased "you ain't (aren't) a hound dog"...it's a "woo-woo" sound
Circle*: both ways, around me or objects
Eight*: both ways, like an "8" shape around me or objects
Put 'em up: front paws up
Paw*: self-explanatory, me or objects
Yea, buddy: both paws, one on each hand
Let's see that @ss: eh that one's my dad's haha...he puts his front paws up on something and pivots around it with his back feet
Sneeze: (can you tell i was getting desperate???)
Yawn: yea...
Wave*: self-explanatory
Knock it over: heehee this one is fun and he gets to be creative
Jump: straight up and down...usually in tandem with me

All-purpose commands:
Through, under, over, up, around*
Touch
Open: refrigerator because he's too short for doors
Beat it/git: general go-away command haha
Go: this one we worked on a lot...basically it's so I can direct him without following him. He does forward, left, and right.
Seek: this is only for scent work-type stuff. I'll give him something to smell (like a food item) and he'll find the rest if I lay a trail. He also will do it with names (like "Dad" or "Hannah")

* in these commands, direction is differentiated by "left" and "right" preceding the command (yes, really)

He has some physical limitations (keep in mind he is 11), and he will NOT take unfamiliar objects in his mouth. Lately I've been making him work harder by putting commands into sentences and trying to link commands (bring Patrick [stuffed starfish haha] and sit), but he's quickly learning that and then we'll be out of things to do.

Also, before anybody starts to thinking that I know what I'm doing...I don't. So if anybody has *ANY* ideas, please please please explain thoroughly how you might go about training them. He's not easily frustrated, but I'm dumb sometimes! I use a clicker and I'm not against luring, but also keep in mind that he is extremely soft.

Please help! Otherwise he will quite possibly start making blueprints for a tank or something....