Today, i'm gonna copy smthg from Yahoo answers that I stumbled upon.
Will there be a season 4 shugo chara?
A:We can't give a direct answer to that question yet. The reason why Shugo Chara Party! ended so suddenly on 25 episodes rather than continuing to 51 like the previous seasons was due to the fact they failed to attract as many viewers unlike the previous seasons(No doubtly for the fact that they got rid out ikuto who was a major impact in the previous seasons for amuto fans)
As for creating a fourth season, There is still a possibility that they will create it as they have just started the second season of the manga called Shugo Chara Encore! which seems like it could follow the old seasons story line. At the end of Shugo Chara Party! there were some unanswered questions which i would really like to know. Hikaru's Guardian egg(It would be cool what he looks like ^^) And my most wanted What will there high school experience be like x3 Oh also they really really need to give us the answer of who amu will get with! In the manga i was really surprised when Kutau actualy happened it was a shock since I only thought it was a fan made couple because it didn't really happen in the Anime or Season One of the manga. So Season 4 can follow that storyline as well But so far there is no confirmed season 4 however there is still a high chance for season 4, I feel there really should be because i'm a major fan of Shugo Chara :D ^^
_Answer by Rena
I also stumbled upon Shugo Chara Encore some time ago and it was only up to Rima & Nagi..
Lazy so i didn't pursue it further. But i saw it again and there AMUTO in it!! >///< (KYAAAA~)
I really support Rena's answer. I REALLLYY want to see Amu in High School (along with Ikutoooo~ < Amuto Fangirl here.~ Lots and lots of unanwered questions i want answered Hmph@!
_TsuwAn Looking foward to SC Encore!