The plugin for VIP Core plugin, will allow you to control how many jumps a player can make per round.
It can be configured to apply restrictions to regular players as well.
sm_bhop_delay "0.4" - Delay in seconds after which the first jump will be counted
sm_bhop_countdown "30" - after how many seconds the player will be able to jump again (reset his counter)
sm_bhop_novip_jumps "0" - Limit on the number of jumps for non-VIP players
Add to groups.ini:
Where 20 - is number of jumps for which you want to set the limit