After I reclass to 25B, and extend to fulfill my obligation, do I have to fulfill the full year before I can submit to reclass again?

If you received a bonus, you will have to repay any payments received and you will forfeit any future payments. Also if you had to extend to full-full the obligation you have to serve in the new MOS once the Army has paid for you to reclass to a new MOS, you’re contractual obligated to fulfill the requirements of the contract. There is a time minimum time obligation once Good luck to you.

SPC (Join to see) Lots of missing information here but I will say my understanding (I am no expert) is you extended to fulfill Not an obligation but a Contract which by what I see completes in January 2021. Violation of a contract can have harsh consequences.
I would think if you want to submit Reclass paper work to any MOS you can do that at any time just don't expect it to get approved until you have completed your current Obligation/contract. This question would be better ask of you COC and or a Career Counselor. JMT