Yeah, I've had this kind of fun and games with Shanti before. You can leave him be until he gets hungry or bored enough to come in by himself. Do you have a catflap you can put on in-only? Also, if he responds to certain sounds like the treat packet crackling or something you could try luring him with that. What I occasionally do with Shanti if I need her to come in is to play a game with her in the garden, which she can't resist, and wait until she's off-guard so that I can grab her.
I pre-empt this game now by not trying to get Shanti in except calling her, then it's up to her if she actually comes through the catflap, but if she does so right away she gets a treat. I also don't let her (or any of them) out after she's been fed. Most of the time she hangs around for 10 minutes or so and then realises I'm not going to play catch-me-if-you-can and comes in by herself.