Here’s some basic alternative techniques when have guard and are doing a kimura shoulder lock but your opponent defends.
The grappling dummy used in this video is the Submission Master from https://grapplingdummy.net.
First, of course, is doing the kimura lock itself.
If he defends, first you can go to a guillotine neck lock.
Next, put your foot to his hip and transition to a straight arm lock with his arm barred against your neck.
If he’s strong and escapes his arm over your head, you can take his back.
Finally, if he wraps your waist and drives you flat to your back, simply collapse your arm and kick over to take mount (since his arm is trapped and he can’t post it out).