If you took your tefillin off to use the bathroom, do you need to make the two brachos again before putting them back on?
It depends on why you were using the bathroom. if it was just to use a urinal, or for urinating, the poskim say that we don’t make a second bracha. The reason for this is because if a person uses a beis hakisay aray (makeshift bathroom, that doesn’t have any refuse there) for urinating he technically doesn’t have to take his tefillin off. Additionally it is controversial if our bathrooms nowadays, since the dirt doesn’t stay there, if it is considered a beis hakisay. Therefore the poskim say that for such a use in our bathrooms we don’t resay the brachos.
However when using the bathroom for defecating, although there are poskim who hold that we don’t re-say the brachos, (Magen Avraham 25:22, Pri Megadim), however most poskim ( Bach,Taz, R’ A. Eiger, Chayei Adam, Radvaz 6:301, Shulchan Aruch Harav 25-30, Maharsham 3:220, and Daas Torah, Ginas Veradim (see Be’er Heitev 53:3), Kitzur Shulchan Aruch 10-15, Mishna Berura 25-47, Biur Halacha D:H V’yesh,) hold that we should re-say the brachos. There are some people who only re-say one of the brachos, (see Shevet Halevi 9-23) however the general minhag is to re-say both of them, as if one is putting on tefillin for the first time.
There is a way to avoid this issue, which is brought in some seforim, that one should state that whenever he will take his tefillin off to use the bathroom (not merely for urinating) that his bracha only extends until then. This way he will then be obligated to say both brachos according to all opinions.
For additional reading see the following post https://dinonline.org/2011/04/07/tefillin-after-bathroom/
Shevet Helevi 9-3, Teshuvos Hanhagos 1-43, Piskei Teshuvos 25-23, Daas Noteh 3-180.