Regarding your family name, the spelling is uncommon so it is an easy name to research. Both variations are found in Lorraine and Alsace, with LEIS mostly in Alsace & Lorraine and LIES mostly in Médoc area of Aquitaine (Bordeaux region) as well as Lorraine.
The spelling LEIS is German origin, and somewhat common in Bayern (Bavaria) and Rheinland-Pfalz (Rhineland-Palitinate), which shares the border with Alsace. In German, it would be pronounced like English « LICE » (and French pronunciation I would say like English « LEE » or « LEASE », but maybe German way is preferred by family.)
The spelling LIES (properly with accent grave LIÈS) is a French variation of LIESSE, which, according to my French Larousse book of Etymology of Family Names, means "happy man." It would be pronounced lee-ESS.
Here also are two name maps you will find interesting from Geopatronyme that shows the distribution of both names in France:
(Note: The source information is excellent for the maps generally, but it is weak for Alsace and Lorraine regions because from 1871 to 1918, they were part of GERMANY not France.)
... and here are links to various German GeoGen name distribution maps for LEIS:http://christoph.stoepel.net/geogen/en/Default.aspx
I checked a French database of Optants - I think it is at Ancestry.com, too, but I did not look at it. I found 8 people named LIÈS who left Alsace and Lorraine after the German annexation (and none for LEIS) which possibly gives a clue that LIÈS is you original name - but this is only a best guess.
Since your name is uncommon, and they left France in the 1890s, there is an excellent chance you will be able to find your family in France. ----- Before you look at French records, be sure to look closely at all of the lines of your ship passenger lists. Ellis Island opened in 1892 and the ship lists from this time forward often (but of course, not always) state the passengers city of origin in France. Also look for naturalization papers in the courthouses of the counties where your family lived. Since they arrived in the 1890s, there was a three step process to become a US citizen. The final naturalization papers seven years after they filed the first papers likely state their town of origin. Also look for will and probates, and family correspondence that your distant family in America might have - you will be surprised.
If you have NO luck, I would begin by searching the Ten-Year Indexes (« Tables décennales ») of cities at the excellent departmental archives in France. (All of the places you need are free and online now except Moselle.) I would start with the cities of LIÈS familes on the Optants list. These French cities are: SELTZ, ROESCHWOOG, DRUSENHEIM, UCKANGE, GAMBSHEIM, and LA WANTZENAU. (Check you Wikipedia for departments.) Also check the Optants list at Ancesty.com for city names. If no luck, then go to the Geopatronyme links I gave you above, and click on the links of department names in the table on the right side of the screen to see the names of the cities, and start checking the 10-Year indexes for each of these cities.
This will be a little bit of work and take several evenings, but it is not unmanageable. (I have done much more difficult research than this and had success locating home cities.)
I wish you good luck !
Bonne quête !