There is no possible generic answer to your question.
First, how do you know it is a premium, as in registry premium? The price you see by registrar is the registrar choice. Did you compare prices among multiple registrars? Did you see the mention premium somewhere? Or did you see it on registry side?
Then, typically, if it is a registry premium, it remains a registry premium even after deletion. However there are certainly exceptions to that, as registries do change their list of premium domains as well as the premium prices, "from time to time".
So the domain can still be premium, and hence will be premium priced for any registration, or it can have left the premium tiers the registry sets, and then a new registration will be standard price.
will get deleted from the registrar in two weeks (counted around 80 days from expire date).
Things are often more complicated than that, and again depends on the TLD.
For gTLDs, see , the Redemption Grace Period is typically 30 days.
But if the price becomes regular price, then thinking of trying to backorder.
Your backorder service should be able to tell you exactly the cost in advance. Registrars can know the price of the domain, hence if it is premium or not, by querying the registry, even if the domain is currently registered. That kind of data however is not exposed publicly and can allow be known through EPP.
You can try to ask the registry directly, but they are in no way required to answer you.