According to Buddhist principles, reincarnation exist, and the goal is to stop the cycle of reincarnation to the physical realm or the desire realm, which we inhabit. To move on to the next "level," one must achieve enlightenment, or the highest yoga tantra to stop the cycle of reincarnation. The desire realm is basically the lowest level, and the higher ones are the form realm an the formless realm.
There are 6 different types of existences, or types of beings in the desire realm. Gods, antigods, human beings, animals, spirits, and hell beings.
Gods (in a permanent state of exaltation, bliss) This is what happens when you free yourself from attachments, which cause suffering
Anti-gods ( Under the influence of hostility, envy, and jealously)
Humans ( under the influence of the 5 dissonant mental states; perception, attention, intention, sensation, contact awareness)
Spirits (Under the influence of attachment and unsatisfactory)
Animals (Under the sway of delusion)
Hell beings (Over taken by hatred, anger, and fear)
It is taught that you will keep coming back through reincarnation until you "get it right" If you don't ascend to the highest level in the physical realm to unlock the next levels, you can still be reincarnated to a favorable life by living righteously; but until you reach enlightenment, you will keep coming back.
Your past actions affect the present and your present action affect your future. This is the law of karma, on which Buddhism is heavily based. The key to true happiness is detachment. Attachment causes desire, which in turn will lead to suffering. Anger causes hatred. Pride causes arrogance, and ignorance causes delusion.