------------Ade---------------
-Eriksen---Lamela---AT/AL/New
--SR/EC or NB/New-P/MD------
R/New--Verts---Kaboul--Walker
-----------Lloris--------------
In an ideal world we would sign a new first choice left back, a new CM who is primarily a deep-lying playmaker a la Modric/Bentaleb, a new right-winger to improve upon Lennon, and a back-up for Walker who can provide more width than Naughton.
Then we would have a balanced and competent defence capable of providing dangerous overlaps (we have struggled this year first with the injury to Rose, then to Walker), someone to 'make us tick' in the middle (mentor to Bentaleb, complementing the destroyers [Sandro/Capoue] and the box-to-box CMs [Paulinho/Dembele]), and a consistent winger who likes to go outside/hit the byline/deliver a good cross (what Lennon is meant to do, complementing Townsend, but fails at achieving with any consistency).
Also: After reflecting on what little we've seen of Lamela prior to his injury, I think he'd be more suited to playing off the striker (he played there for River if I'm not mistaken). He doesn't really have the pace to play on the wing in England, and Eriksen offers more coming in from the wing. Playing centrally might afford him more chances to use his clever flicks and vision to unlock the defence, while he could also make the in-to-out 'central-winger' (to use Michael Cox's terminology) runs that would both create confusion and space centrally and allow him a bit more time on the ball to utilise his undoubted technical ability.
From Eriksen, Lamela plus 2 of Chadli/Sig/Holtby we would have a pretty diverse pool of players to pick the inside-left and attacking midfield positions outlined at the start of this post.
In short: No, I would not keep the same squad for next season. We do not need much other than time, but 3 or 4 signings could revitalise our squad and begin to form a coherent team out of the mass of individuals assembled last summer, which have begun to gel in parts this year but clearly need further additions to fully utilise.