From Here: http://www.aish.com/tp/i/moha/48955486.html
The Main Points:
Rashi [7] suggests that the name
Yaakov indicates subservience, while
the name Yisrael indicates strength
and victory. Varying uses reflect
different aspects of Yaakov's
personality that come to light in
varying situations. Another view is
offered by Meshech Chochma, who sees
the different names as expressing the
distinction between Yaakov as an
individual versus Yisrael as a
national identity. Thus, according to
Meshech Chochma, God addresses
"Yisrael" exclusively when, and only
when, there are national issues at
hand. [8]
The Netziv [9] proposes that the
distinction is between a supernatural
aspect (Yisrael), versus a more
mundane name (Yaakov) used when
natural events or actions are
described. Because humans cannot
function purely on the spiritual
plane, both names are needed.
Each of these suggestions seems to
point to an unresolved tension in
Yaakov's life which results in a dual
identity.
[7] Rashi Bereishit 35:10, this idea
is echoed by Rabbenu Bachya 32:29.
[8] Meshech Chochma Bereishit 35:10.
[9] Ha'amek Davar Bereishit 35:10, see
Rabenu Bachaya 47:29 who see Yaakov as
a name indicating physicality, and
Yisrael as a name indicative of the
spiritual.