make a midi performance half time

i have a midi track of a drum beat i made for a song that i want to use in another song. when i import it into the second song, it is playing double time, which is probably how i had it playing in the first song, but the tempo was so different, it sounded different... anyway. i want to take that performance, say its 32 bars, and maintain the relationship between all of the midi notes and make it play half as fast, therefore making the performance 64 bars... i hope that makes sense. i know i can change the tempo of the song until it sounds right, but i already have the rest of the song at the tempo i want and i dont want to change everything...

thanks.