It is possible to replace your PRL manually.
1) You will need to know your MSL (Master Subsidy Lock) code.
There is no known way of getting it from an unrooted Admiral.
Some have had success asking for it from Sprint directly via chat/call, or from the Sprint store.
2) You will have to download the appropriate PRL.
The Admiral supports 800MHz SMR but not LTE.
As of time of writing, my stock PRL was 60690.
I went to 12124 which provided 3G when roaming (vs 1x) and is the PRL provided to corporate accounts.
BatonRougeBroadband.Info - Home
is a useful site that analyzes the PRL files but you won't be able to download it from there. A simple google search for prl and the ##### you want will likely yield results.
BEWARE of using the infamous 00000.prl or 00001.prl which will pretty much put you on Verizon and result in excessive roaming use, resulting in Sprint terminating your agreement.
3) You will have to use a program like QPST to "push" the new PRL file to your phone.
Again, you need your MSL to be able to do this. There are detailed instructions available on other sites and on youtube on how to use QPST. If used incorrectly, QPST can permanently damage your phone as it can change many internal settings and values that should not be changed. You should proceed very carefully and assume all risks.
As always, please understand that if done incorrectly, you can break your phone. Also, changing PRL's can affect the quality of your service, the amount of roaming data you use (which can result in termination of your account).
I opted not to post links to other forums and directly to the files (at this time), so please treat this post as informational only.
Depending on the opinion of the mods and if there's interest, I can post additional information, includng links to instructions and/or files. They are not created by me, I came across them when browsing other "Android" related news and found it works on the Admiral