The one year criterion is for those who are out of status. If you can show a valid reason to apply for asylum and you are in status, you can still file a petition for asylum even after one year of stay in the US. However, you have to show some recent developments in Nepal that makes it unsafe for you to go back home.

One more thing. If you apply for asylum while on student visa and if your asylum application is denied by the immigration court, you can no longer maintain your student status and you will have to return home (or go out of status) since you showed intent to stay in USA by applying for asylum.

I hope this information helps.