My dog lost interest in jumping?

i have been jumping my mutt, butch, for little over a year now. he is a fantastic jumper, but he doesn't respond to me quickly anymore. i use a gentle, cheerful voice, and now he seems AFRAID of me! i have tried to make jumping interesting, with toys and colorful bard and such, and using squeaky toys, but he just seems to have lost heart. do you have any suggestions?