"Againやはり" is used mainly in the text (writing), "Yappariやっぱり" is used in oral.

矢っ張り【やっぱり】it is two words joint together 矢張り【やはり】it is two words gouping together Both means the same, as I thought; still; in spite of; absolutely; of course etc. The only difference is the pronounciation. It is similar to the American English, eliminated sound. For example: peanut butter, pronounce "peanut budda". The " tt" is changed to "d" sound.