  BL Lacertae (BL Lac) objects are the prominent members of the third {\it
Fermi} Large Area Telescope catalog of $\gamma$-ray sources. Half of the BL Lac
population ($\sim$ 300) lack redshift measurements, which is due to the absence
of lines in their optical spectrum, thereby making it difficult to utilize
spectroscopic methods. Our photometric drop-out technique can be used to
establish the redshift for a fraction of these sources. This work employed 6
filters mounted on the $Swift$-UVOT and 4 optical filters on two telescopes,
the 0.65 m SARA-CTIO in Chile and 1.0 m SARA-ORM in the Canary Islands, Spain.
A sample of 15 sources was extracted from the $Swift$ archival data for which 6
filter UVOT observations were conducted. By complementing the {\it Swift}
observations with the SARA ones, we were able to discover two high redshift
sources: 3FGL J1155.4-3417 and 3FGL J1156.7-2250 at $z=1.83^{+0.10}_{-0.13}$
and $z=1.73^{+0.11}_{-0.19}$ , respectively, resulting from the dropouts in the
powerlaw template fits to these data. The discoveries add to the important (26
total) sample of high-redshift BL Lacs. While the sample of high-z BL Lacs is
still rather small, these objects do not seem to fit well within known schemes
of the blazar population and represent the best probes of the extragalactic
background light.
