Hey, no there is no way to "reactivate" the trial once it has expired. However, you can "upgrade" to the free plan via https://railway.com/workspace/plans to try out the platform with limited resources.

Hey

I want to use it and understand some plan where I get 1 cpu core or things like that for 5$ or so ?

Hey, in this case, you can just upgrade to the hobby plan, since the hobby plan starts at $5.